The present invention provides a car sharing system configured to achieve improvement of operation of a mobile terminal to allow a vehicle machine to perform response and safety maintenance when motion. The car sharing system (21) includes a car share device (23) and a communication control unit (41). The communication control unit (41) controls the wireless communication between the mobile terminal (22) and the car share device (23) so that an authentication process through bidirectional communication is executed only when a communication connection establishment process is performed. After the wireless communication has been established, the communication control unit (41) controls the wireless communication so that actuation of an on-board device (3) is permitted in accordance with operation of the mobile terminal (22) through unidirectional communication from the mobile terminal (22) to the car share device.