To reduce noise in a paper detection unit for detecting the passage of a paper just after being heated and pressurized, which is assembled in a fixing device.

The paper detection unit includes a first member whose attitude is changed between a first attitude where the first member interferes with the paper after passing through between a pair of fixing rolls and a second attitude where the first member is rotated from the first attitude, a second member whose attitude is changed between a third attitude and a fourth attitude, a sensor for detecting the attitude of the second member, a connection shaft for connecting the first member and the second member, an energizing member for energizing the connection shaft in a direction where the first member is changed from the second attitude to the first attitude, and a receiving member having such a shape that the receiving member is projected in a cantilever shape from the inner surface of a housing in the rotation axis direction of the fixing roll and receiving and stopping the second member to hold the first member still at the first attitude through the connection shaft.