Abstract: A heat generating apparatus includes a rotary shaft, a heat generating drum, a plurality of permanent magnets, a magnet holding ring, a switching mechanism, and a heat recovery system. The magnets are arrayed in a circumferential direction along the circumference of the rotary shaft throughout the whole circumference such that magnetic pole arrangements of circumferentially adjacent ones of the permanent magnets are opposite to each other. The magnet holding ring holds the magnets. The switching mechanism switches between a state to generate magnetic circuits between the magnets and the heat generating drum and a state to generate no magnetic circuits between the magnets and the heat generating drum. The heat recovery system collects heat generated in the heat generating drum. Thereby, thermal energy can be recovered from the kinetic energy of the rotary shaft efficiently.