An image forming apparatus includes (i) a housing including a first connector, (ii) a drum unit, (iii) a development unit including a containing portion containing toner and movable between an abutment position and a separation position, (iv) a detection unit including a light emitting element, a light receiving element, and a second connector electrically connected to the light emitting element and the light receiving element, and mounted on the development unit, and (v) a connection member connected to the first connector and the second connector to electrically connect the first connector and the second connector each. A length of the connection member is longer than a first distance from the first connector to the second connector when the development unit is located at the abutment position, and is longer than a second distance from the first connector to the second connector when the development unit is located at the separation position.