A heating unit includes a to-be-engaged portion. A fixing unit includes an engagement portion. The heating unit or the fixing unit includes an engagement guide portion. A movement mechanism retains the heating unit in a tilted attitude when causing the heating unit to move at a position set apart from the fixing unit. The engagement guide portion causes the heating unit to rock from the tilted attitude to a reference attitude while guiding the to-be-engaged portion to the engagement portion. The engagement portion engages with the to-be-engaged portion to restrict a movement of the heating unit in a longitudinal direction. A unit bias portion retains an engagement state between the engagement portion and the to-be-engaged portion.