An image forming device includes: a collecting container that collects a waste toner; a rotation member that rotates and spreads a waste toner inside the collecting container; a torque detection unit that detects torque applied to the rotation member by a waste toner inside the collecting container; and a rotation direction switching unit that switches a rotation direction of the rotation member. When a torque value detected by the torque detection unit is more than a first threshold, the rotation direction of the rotation member is switched by the rotation direction switching unit.