A fixing device includes a heat rotor with a heat source, a pressure rotor forming a fixing nip with the heat rotor and expandable by heat given from the heat rotor, a drive section configured to rotate the pressure rotor, a control section configured to control the drive section, thus controlling a rotational speed of the pressure rotor, and a heat quantity detecting section configured to determine a quantity of heat from the heat rotor to the pressure rotor since a reference time point when the fixing device transitions from outage to operating state. The control section performs a first rotation control for allowing the pressure rotor to rotate at a first rotational speed after the heat quantity detecting section detects the quantity of heat has reached a predetermined specified value and at a second rotational speed before the heat quantity detecting section detects the specified value has been reached.