An image forming apparatus has a sheet feed cassette to store a sheet supplied to the image forming apparatus. The sheet feed cassette has a cassette body and a cassette cover. The cassette body stores the sheet and has first and second cassette portions coupled adjustably in length. The cassette cover is detachably mounted on the cassette body to cover its upper portion and has first and second cover portions coupled adjustably in length. The cassette cover has a fitting portion, and the cassette body has fitting receive portions in the first and second cassette portions. Each of the fitting receive portions is fittable with the fitting portion. The fitting receive portions overlap in a sheet feed direction when the cassette body is retracted. Of the fitting receive portions, one fitting receive portion not fitted with the fitting portion when the cassette body is extended is at least partially closed.