In an apparatus for producing trichlorosilane, an internal space of a reaction chamber is partitioned in a radial direction by first walls running along a circumferential direction, and is partitioned into multiple spaces by second walls which extend in a direction crossing the circumferential direction. Upper portions or lower portions of the first walls and the second walls are formed with a communicating portion which circulates a raw material gas to be introduced, toward a central portion of a reaction chamber while the raw material gas goes through the small spaces sequentially and is turned up and down, heaters are installed in the small spaces, one of small spaces on both sides of the second walls is used as a small space for a upward flow passage, and the other is used as a small space for a downward flow passage, and the small spaces communicate with each other via the communication portion of the second walls.