This article discusses the key issues regarding the newest concept of the legal regulation of working time through the prism of trends in the development of society, the state, and the labor market. The chief attention should be paid to the issues of the priority of requests and interests of employees, the formation of effective mechanisms of social partnership, and the trends of the international labor market. Critically comprehended is the state of legal regulation of working time. It is stressed that, from the legal point of view, the current state of the legal regulation of working time appears somewhat vulnerable, taking into account the following factors: the non-compliance with the state of labor market development; inefficiency, ineffectiveness of legal regulation; the lack of proper motivation of labor productivity, taking into account the necessity of guaranteeing the life, health, and efficiency of every worker; the lack of proper mechanisms for organizing the working time, including modern, innovative jobs; insufficiency of legal mechanisms for the use of information and other technologies of working time control; lack of quality mechanisms for the implementation of international social standards; absence of an optimal combination of the working time, rest time, and occupational safety; the lack of proper mechanisms for taking into account the needs and interests of persons with disabilities and other socially vulnerable categories of persons; the lack of effective oversight and control; the lack of jurisdictional protection, etc.The paper discusses the importance of a proper assessment of the problems of the legal regulation of working time in the present, given the importance of the integration processes of labor market development, its international vector, the introduction of the newest information and other technologies, the implementation of international (European) standards, the formation of mechanisms for the optimal combination of legislative, sub-legislative and the local regulation in this area. In addition, the issue of particular importance is raised in the context of the recent codification of labor legislation as a component of developing an effective concept of the legal regulation of working time. The modern system of principles of the legal regulation of working time is outlined. It is concluded that working time is a period during which an employee, as a rule, must be in the workplace, subject to the control of the employer and other established rules, must perform the labor function and other duties under the employment contract. The main features of the working time are as follow: regulated on the basis of international legal acts, acts of domestic national legislation, local normative legal acts; the worker is subject to established working time norms and rules; directed to the behavior of the employee and the employer under an employment contract (correlates with the system of rights, responsibilities, responsibilities of the employee and employer); payable; accompanied by a system of international standards on labor issues; accompanied by a system of social and labor guarantees; time, intended to perform labor function and other duties under an employment contract; the employee is subject to control by the employer (the authorized body or official); subject to accounting, control and supervision; subject to jurisdictional protection.It is emphasized that the principles of the legal regulation of working time are the basic principles and provisions that determine the peculiarities of the legal regulation of relations in the sphere of working time.The basic general principles of the legal regulation of working time are the following: the rule of law; humanism; social justice; priority of the maintenance of the working capacity, the health and life of workers; the priority of international (European) standards in the field of working time; the priority of the legislative regulation of relations in the field of working time.The main special principles of the legal regulation of working time are the following: inclusiveness, efficiency, and accessibility; the priority of needs and interests of employees; stimulation of labor productivity; ensuring the efficiency of work of persons with disabilities and other socially vulnerable categories of persons; the principle of social partnership; versatility, flexibility of types and working hours; implementation of international (European) standards in the field of working time; a combination of legislative, contractual, and the local legal regulation of working time; combination of working time and rest time, occupational safety; the principle of unity and differentiation of the legal regulation of working time. The fundamental trend of improving the legal regulation of working time is the implementation of the newest codification of the labor legislation through the adoption of a modern socially oriented TC that has a holistic, comprehensive, and systematic regulation of working time relations.Article received 03.03.2019