A fixing member is supported so as to be displaceable in a crossing direction that crosses a sheet conveying direction. A pressure member rotationally drives the fixing member by being rotationally driven. A motor rotationally drives the pressure member. A biasing mechanism elastically biases the fixing member toward the pressure member. A sheet detection portion detects a sheet at a first position and a second position. The first position is a position between a mechanism that feeds the sheet to a fixing position and the fixing position in the conveyance path. The second position is a position between the fixing position and a mechanism that takes over conveyance of the sheet from the fixing device. A control device times a time required for detection results from the sheet detection portion to show a predetermined change, and controls a rotational speed of the motor according to the timed time.