Fixing device and image forming apparatus

A fixing device comprising:

• an endless belt rotatable in a given direction of rotation;
• a heater disposed opposite and heating the endless belt;
• a nip formation pad disposed opposite an inner circumferential surface of the endless belt;
• and
• a pressing rotary body pressed against the nip formation pad via the endless belt to form a fixing nip between the endless belt and the pressing rotary body, the fixing nip through which a recording medium is conveyed, the pressing rotary body having a diameter increasing from a center to each lateral end in an axial direction thereof,
• the nip formation pad including a projection disposed downstream from a rotation axis of the pressing rotary body in a recording medium conveyance direction, the projection projecting toward the pressing rotary body in an amount increasing from each lateral end to a center in a longitudinal direction of the nip formation pad parallel to the axial direction of the pressing rotary body.