The pinch detector includes a first portion that, in a first situation in which the member is being closed in a first closing movement but is stopped in an intermediate position not completely closed, obtains a reference value of a measured physical quantity of the motor, when braking the motor is ordered to stop the member, said reference value representing the physical quantity of the motor just before motor braking; a second portion that, in a second situation following the first situation and in which the member is moved in a second closing movement from said intermediate position not completely closed, compares current values of the measured physical quantity of the motor to a threshold value depending on said reference value in order to detect a pinch at closing member based on a comparison result.