A fixing device includes a fixing belt, a pressuring member, a pressing member and a sheet member. The sheet member is disposed between the fixing belt and the pressing member. The sheet member includes a sliding contact part, an upstream side fixed part, a downstream side fixed part and a loose part. The sliding contact part comes into sliding contact with the inner circumference face of the fixing belt. The upstream side fixed part is fixed to the pressing member at an upstream side of the sliding contact part. The downstream side fixed part is fixed to the pressing member at a downstream side of the sliding contact part. The loose part is formed in at least one of an area between the sliding contact part and the upstream side fixed part and an area between the sliding contact part and the downstream side fixed part.