A walking beam type heat treatment apparatus including a heating furnace having a heating body to heat a substrate by radiation, a pair of first beams that are rod-like and provided in the heating furnace and a second beam disposed between the pair of the first beams, one of the pair of the first beams and the second beam relatively moving alternately in longitudinal and vertical directions repeatedly to the other of the pair of the first beams and the second beam, to cause to deliver and receive the substrate between the pair of the first beams and the second beam, and accordingly, to convey the substrate through the heating furnace, includes a side edge support protrusion that protrudes from each of the pair of the first beams such that the side edge support protrusion can horizontally support the substrate in abutting contact with a side edge of the substrate; and a front edge support protrusion and a rear edge support protrusion that protrude from the second beam such that the front edge support protrusion and the rear edge support protrusion can horizontally support the substrate in abutting contact with a front edge and a rear edge of the substrate.