An image forming apparatus has a rockable member which is configured to rotate about an axis defined at a first end portion among: a first position at which a second end portion at a downstream side in the forward feed direction with respect to the first end portion is supported by the guide member having the first orientation; a second position at which the second end portion is located at a higher position that the second end portion when located at the first position; and a third position at which the second end portion is located at a lower position that the second end portion when located at the first position; and a signal generating unit configured to output a signal corresponding to the position of the rockable member. A photo sensor is provided to generate a signal in accordance with an orientation of the rockable member.