A fixing device includes a fixing belt, a pressuring member, a pressing member, a guiding member, a cap member, an elastic member and a detecting mechanism. The pressing member includes a pressing face pressing the fixing belt to a side of the pressuring member. The fixing belt includes a bulging part arranged at the downstream side from a fixing nip in a conveying direction. The cap member includes a facing part facing to the bulging part. Before the pressuring member comes into pressure contact with the fixing belt, a gap is arranged between the bulging part and facing part. When the pressuring member comes into pressure contact with the fixing belt, the bulging part bulges toward an external diameter side of the fixing belt to fill up the gap and the cap member is held by an end part of the fixing belt via the elastic member.