A detection apparatus includes a rotating member which rotates in a rotation direction from a standby posture by being pushed by a conveyed sheet, a sensor of which an output is changed as the rotating member rotates from the standby posture, an elastic member which elastically applies a force to the rotating member in a direction opposite to the rotation direction, a first abutting portion which abuts onto the rotating member applied by a force by the elastic member to maintain the rotating member in the standby posture, and a regulation unit which allows the rotating member to rotate in the rotation direction by being pushed by the conveyed sheet and regulates the rotating member not to rotate in the rotation direction by a repulsion force when the rotating member rotated in the opposite direction by an elastic force of the elastic member abuts onto the first abutting portion.