Despite its negative impact on patients and nurses, the use of restraint in somatic health care continues in many settings. Understanding the reasons and justifications for the use of restraint among nurses is crucial in order to manage this challenge. To understand nurses' justifications for restraint use in neurosurgical care. A qualitative, descriptive design was used. Data were analysed with inductive qualitative content analysis. Semi-structured interviews with 15 nurses working in three neurosurgical departments in Sweden. Approved by The Regional Ethics Committee, Stockholm, Sweden. The analysis resulted in three categories. The category Patient factors influencing restraint use describes patient factors that trigger restraint, such as a diminished decision-making competence, restlessness, and need for invasive devices. The category Specific reasons for justifying restraint describes reasons for restraining patients, such as restraint being used for the sake of the patient or for the sake of others. The category General reasoning in justifying restraint describes how nurses reason when using restraint, and the decision to use restraint was often based on a consequentialist approach where the nurses' weighed the pros and cons of different alternatives. Nurses with experience of restraint use were engaged in a constant process of justifying and balancing different options and actions. Restraint was considered legitimate if the benefit exceeded the suffering, but decisions on which restraint measures to use and when to use them depended on the values of the individual nurse. How nurses reason when justifying restraint, why they use restraint, and who they use restraint on must be considered when creating programs and guidelines to reduce the use of restraint and to ensure that when it is used it is used carefully, appropriately, and with respect.