An intermediate transfer unit includes an intermediate transfer belt, a plurality of transfer rollers, a housing, and a filter unit. The intermediate transfer belt is mounted around a drive roller and a driven roller and capable of traveling in an endless path around the rollers. The housing holds the intermediate transfer belt and the transfer rollers. The filter unit includes: a suction portion; an exhaust portion; and a rectangular chassis provided internally with an upstream filter and a downstream filter both capable of collecting powder particles. The filter unit is disposed inside of the intermediate transfer belt so that a direction of length of the chassis is oriented parallel to a direction of width of the intermediate transfer belt perpendicular to a direction of travel of the intermediate transfer belt, and the filter unit is fixed to the housing.