An impact detecting apparatus has a housing having a conical slope therein and a ball located on the conical slope. A shaft is located within the housing and movably supported on the housing for striking the ball with one end. A fixed electrode is located within the housing and a movable electrode is located near the fixed electrode. The movable electrode electrically connects with the fixed electrode. A lever is rotatably and slidably supported within the housing. One end of the lever is able to push the movable electrode and the other end of the lever is able to contact with the shaft. A spring urges the shaft for striking the ball.