According to the present invention, there is provided a fungal bed cultivation method of a hon-shimeji mushroom, wherein induction of primordia of a fruit body is conducted by illumination under incubation conditions, and an ongoing culture for fungal bed cultivation of a hon-shimeji mushroom, wherein primordia of a fruit body have been formed thereon during incubation. The culture medium is maintained in a clean state and it is advantageous because the formation of primordia of a fruit body can be carried out in a clean environment and the culture medium wherein primordia of a fruit body have been formed can be transferred to distant mushroom cultivation facilities under clean conditions as such.