| 摘要 |
A fixing device (100; 200) includes a hardness adjusting unit (150, 155; 250, 255, 260, 265) to adjust hardness of an outer circumferential surface of a fixing belt (140) at a nip (N2). When a sheet (P) to be passed through the nip (N2) is an envelope and the envelope is passed through the nip by side-flap sheet passing for feeding the sheet so that a fold line between an envelope body and a flap extends in a sheet passing direction through the nip (N2), the hardness adjusting unit brings the outer circumferential surface of the fixing belt (140) at the nip (N2) during passage of the sheet than when the sheet (P) into a softer state is a plain sheet. |
