An image forming apparatus includes: an image forming portion; a pair of rotatable members, at least one of which is an endless belt; a contact-and-separation portion; a driving portion; a detecting portion configured to detect presence or absence of the sheet and another object on a sheet feeding path downstream of a fixing nip with respect to a sheet feeding direction; and an output portion configured to output a signal indicating breakage of the belt upon detection of the presence of the object on the sheet feeding path by the detecting portion when said rotatable members are spaced from each other and the belt rotates.