An optical fiber reinforcing heating device 6A is equipped with a base part 12, while the base part 12 is provided with a sleeve accommodation groove that contains a fiber reinforcement sleeve and a heater having a U-shaped cross section, which heats the fiber reinforcement sleeve. A pair of fiber holders 19 that holds and clamps fusion-spliced optical fibers 3 are disposed on both end sides of the sleeve accommodation groove. A lid part 23 that covers the fiber accommodation groove 13 is attached openably and closably to the base part 12 through a rotary axis. A protector 24 for windbreak and heat insulation is joined to the lid part 23 through a rotary axis 25. The protector 24 is a member for preventing winds from entering the sleeve accommodation groove from a gap between a side wall of the base part 12 and the lid part 23.