Conveyance speed of recording materials by a fixing roller pair can be set to conveyance speed based on detected results of a recording material detector and a loop detecting sensor, and information on the recording material that has been stored in a memory in advance, and the conveyance speed of the fixing roller pair is set so that loop length of the recording material will be a lower limit length, after the loop detecting sensor detects a loop of the recording material, and before the rear end of the recording material passes through the transfer roller pair.