To let an engine be automatically suspended at proper timing permitting no sense of incongruity to be given to a driver by estimating the continuous period of time for keeping a specified running condition based on running environmental information received by wireless, and by automatically suspending the engine when it is found that the aforesaid continuous period of time is greater than the specified period of time.

This device is equipped with running condition detecting means 3 and 4 detecting the running condition of a vehicle, and with running environmental information receiving means 1 and 2 receiving the running environmental information of a vehicle transmitted from the outside. When a specified running condition is detected out of the running conditions detecting means 3 and 4, the continuous period of time for the specified running condition is thereby estimated based on the result of receiving from the running environmental information receiving means 1 and 2, and when the continuous period of time is found to have been greater than the specified period of time, the engine is thereby automatically suspended.