An image reading apparatus includes placement member, pressing member, and open/close detection portion. Open/close detection portion detects opening and closing of pressing member. Open/close detection portion includes movable portion, guide hole, and sensor. When pressing member is opened, movable portion moves toward one side, thereby protruding to an area between placement member and pressing member, and when pressing member is closed, movable portion moves toward the other side. Movable portion extends along movement direction thereof. Guide hole of movable portion guides movement of movable portion in movement direction. Movable portion has a plurality of groove portions extending in movement direction, and groove portions partially include guide groove. Guide hole has guide protrusion protruding from inner circumferential surface thereof toward groove portion of movable portion, so as to guide movement of movable portion. Guide protrusion is formed only at position opposing to guide groove, of groove portions of movable portion.