A device for detecting a holding state of an object. The device includes a housing for the object that has a shape that can be held by an operator and a piezoelectric sensor attached to the housing. Moreover, a detecting unit can detects a holding state of the housing by using a fluctuation amount of an output voltage of the piezoelectric sensor. The housing has a shape having a hollow space and the piezoelectric sensor has a flat film shape and is disposed in contact with an inner wall surface of the housing. The piezoelectric film produces charges when stretched and contracted in response to a displacement of the housing that are outputted as a voltage to the detecting unit. When detecting that the output voltage significantly fluctuates, the detecting unit identifies that the object is being held.