A retaining unit retains a plurality of photosensitive drums and includes a first conveying member. A main casing has a first conveying path and a second conveying path. The first conveying path extends from a first supplying unit to a first position where a second transfer unit opposes a downstream end portion of a first transfer unit. A first transferred medium is conveyed along the first conveying path in a conveying direction. A second transferred medium extends from a second supplying unit to a second position located upstream of the first position in the conveying direction. The second transferred medium is conveyed to the first conveying path through the second conveying path. The first conveying member is configured to convey the second transferred medium supplied from the second supplying unit in the second conveying path.