A PTO shaft driving device in a working machine, includes a parking switch to detect parking of a vehicle body, a first switch located on a manipulator located on the vehicle body to output a PTO shaft control command that is either a driving command to drive a PTO shaft located on the vehicle body or a stopping command to stop the PTO shaft, a second switch located at a position different from the manipulator to output a PTO shaft control command that is either a driving command to drive the PTO shaft or a stopping command to stop the PTO shaft, a first permission switch to selectively permit or prohibit a stationary work when the parking switch detects the parking, and a controller configured or programmed to control driving of the PTO shaft. The controller is configured or programmed to selectively drive or stop the PTO shaft according to the PTO shaft control command from the first switch or the second switch when the stationary work is permitted by the first permission switch.