Image forming apparatus capable of suppressing deterioration in image quality

An image forming apparatus includes a photoelectric conversion portion, a housing, a housing support portion, and a posture adjustment portion. The photoelectric conversion portion receives light reflected by a document sheet placed on a document sheet mounting surface and outputs an electric signal based on the light. The housing has a box shape with an open top and forms a housing space for housing the photoelectric conversion portion on a lower side of the document sheet mounting surface. The housing support portion supports a bottom portion of the housing. The posture adjustment portion includes an operation portion provided outside the housing, and adjusts a posture of the photoelectric conversion portion in accordance with an operation on the operation portion.