An image forming apparatus has a main body, a belt unit configured to accommodate a belt, a belt cleaning member and an accommodating unit. The belt cleaning unit is configured to remove waste toner adhered on the belt. The accommodating unit is configured to accommodate the toner removed by the belt cleaning unit. The apparatus further includes a drum unit having a drum cleaning member, and a waste toner conveying mechanism configured to convey the waste toner to the collecting unit. The conveying mechanism has a drum-side conveying unit configured to be connected with the drum cleaning member. Communication between the drum-side conveying unit and the collecting unit is enabled in association with movement of the drum unit from the outside position to the inside position, and disabled in association with movement of the drum unit from the inside position to the outside position.