A belt-type fixing device is provided that allows reduction in driving torque for a fixing belt without deteriorating performance of heat transfer from a heating roller to the fixing belt.The belt-type fixing device of the present invention has an endless-sheet-like fixing belt to be heated that is wound around a rotatable heating roller and around a nip forming member fixed so as to be incapable of rotating, and has a pressurizing roller that can be driven to rotate and that is in pressure contact with the nip forming member with the fixing belt interposed between. Contact part between the fixing belt and the pressurizing roller forms a fixing nip. For a tension load W [N] on the fixing belt that is driven and rotated by the pressurizing roller, and a width L [m] of the fixing belt, W/L is set in a range from 18.0 to 107.9 [N/m].