To efficiently calculate a wages by setting a late-night time zone or late-night premium rate for each employee.

A data processing means 12 acquires the working hour data of an employee expressed by identification data inputted from an identification data input means for each working day within a specified period from a filing device 10, finds working hours in the late-night time zone for each working day by collating these working hour data with time zone data inputted from a time zone data input means 6 and totals these working hours within the specified period later. Thus, even when setting of the late-night time zone and the late-night premium is different for each employee, the wages can be efficiently calculated by using the working hour totaled result in the late-nigh time zone and the late-night premium rate inputted by a premium rate data input means.