A washing machine includes: a drum that rotates with a washing or drying object contained in the drum; a motor that rotationally drives the drum; a controller that controls rotation of the motor; and an electric current measurer that measures an electric current value representing an electric current flowing in the motor. The controller controls the rotation of the motor to rotate the drum less than one turn, and in accordance with the measured electric current value, detects whether a foreign object that is different from the object and whose mass is greater than an expected mass of the object is inside the drum. In a case where the controller detects the foreign object, the controller stops operation of the washing machine.