A fixing device includes a rotatable fixing belt, a pad, a rotatable pressing member, a pressing member driving source, an auxiliary driving roller, and a transmission mechanism for transmitting a driving force from the pressing member driving source to the auxiliary driving roller, wherein a peripheral speed of the auxiliary driving roller is faster than a peripheral speed of the pressing member, and a steering roller provided so as to stretch the fixing belt at the inner surface of the fixing belt in a position downstream of the auxiliary driving roller and upstream the pad with respect to a rotational direction of the fixing belt. The steering roller adjusts a position of the fixing belt with respect to a widthwise direction of the fixing belt by inclining the fixing belt so as to be positioned within a predetermined range.