Recently, size of information system gets large, and the information system operation (IT operations) is often outsourced. When IT operations of the large system is outsourced, high cost is needed, and troubles in IT operations may affect the activity of the company. Therefore, the information system operation is important for the companies. Cost is one of the important factors when the system operation is outsourced. However, it is not easy for the customers (system users) to judge whether the operation cost is valid or not. To support the judgment, we focus on information which the customers can know (e.g., size of software), to estimate the working time. In the analysis, we clarified the factors which affect the working time. Then, data was stratified based on the factors, to show the benchmark of working time. Using the benchmark, customers estimate the working time roughly. Also, we clarified the factors which affect the unit cost, and showed the benchmark. Operation cost can be estimated, by estimated working time multiplied by the estimated unit cost. The analysis results showed that the process standardization relates to the working time of operators. Also, the network range and the contract type have a relationship to the unit cost of operators. Work efficiency and unit cost do not affect operation quality. • We clarified the factors which affect the working time and the unit cost of the operators, using a cross-company dataset. • The process standardization relates to the working time of operators. • The network range and the contract type have a relationship to the unit cost of operators. • Work efficiency and unit cost do not affect operation quality explicitly.