Provided is a heat treatment device for an optical fiber reinforcing member, whereby optimum heating conditions can be set in accordance with a voltage applied to a heater. A heat treatment device (10) for an optical fiber reinforcing member is provided with a fiber holding unit (11) capable of holding an optical fiber in which a fusion-splice is covered by a reinforcing member, a heater (12) capable of heating the reinforcing member, a power source unit (14) for applying a voltage to the heater (12), and a control unit (20) for controlling the application of voltage to the heater (12) from the power source unit (14). The control unit (20) is provided with a detecting unit (21) for detecting a parameter for calculating the amount of heat generated by the heater (12), a storage unit (22) for storing a plurality of heating conditions that differ for each parameter value, and a condition instruction unit (23) for selecting any of the plurality of heating conditions in accordance with the parameter value detected by the detecting unit (21) and instructing the power source unit (14) to apply voltage to the heater (12) on the basis of the selected heating condition.