provided is an engine starting system which is highly reliable in that a battery does not run out even if a manual switch is tampered and operated many times by a third party . equipment on the propelled object side includes an actuation signal refusing unit which avoids responding to an actuation signal from a switch for a third predetermined time in at least one of the states where a number of actuation signals successively transmitted from the switch without producing an answer signal thereto has become equal to or larger than a prescribed number of times predetermined in a first predetermined time period and where the actuation signal has been kept tuned on for a period equal to or longer than a second predetermined time period without producing an answer signal thereto .