To provide an operation management system which allows a driver to manage his/her own on-duty hours.

A taximeter 10 displays remaining monthly on-duty hours recorded in a memory card 40 on a display part 12 when a driver inserts the memory card at the time of leaving a garage (S15). Meanwhile, a data processor 50 reads labor hour data from the memory card 40 when the memory card is inserted into a card reader 54a (S3). The data processor updates labor hour data in a storage memory 56 based on the read labor hour data (S4). At the time, the remaining on-duty hours are calculated from daily on-duty hours (time when leaving the garage - time when entering the garage) to update them. The updated remaining on-duty hours are written in the memory card 40.