The present disclosure provides an entrance and exit position detection device for a power device. The entrance and exit position detection device for a power device comprises: a cradle which is open on one side and has an arrangement space formed therein; a power device body which may be in the arrangement space and has a guide plate formed on one side portion thereof; and a position detection part which linearly detects the displaced position of the power device body while the cradle enters and exits the arrangement space. Also, the present disclosure provides an entrance and exit monitoring system which has the above-described entrance and exit position detection device for the power device.