Abstract: A sensor part detects an actual driving signal in the driving time by a pneumatic tool. A control part, based on the detected actual driving signal, makes an addition to the actual driving number which has already stored in a memory part to updates the actual driving number, and compares the updated accumulative actual driving number with the previously set basic maintenance number. As a result of the comparison, in case the accumulative actual driving number exceeds the basic maintenance number, it is determined that maintenance is necessary for the pneumatic tool. A light emitting part emits the light and blinks by an instruction from the control part, thereby to warn a user that the pneumatic tool is into the maintenance time. Hereby, the user can grasp the maintenance time of the tool surely and exactly.