To dry a mushroom in a uniform finished state in each of drying chambers by a method wherein a gas discharging hole arranged at a ceiling section of a drying chamber corresponding to a sensing means is closed, flow of hot air into the drying chamber is restricted and flow of the hot air into another drying chamber is promoted as the flow of the hot air is restricted.

A first drying chamber 1 and a second drying chamber 2 are formed into a pair of right and left boxes having a predetermined capacity. A predetermined heat insulating panel is arranged at a wall section and then some mushroom shelves 13 having multi-stage nets therein are arranged in the panel in such a way that they may be freely pushed into or pulled out of it. Each of the first and second sensing means 10, 11 is arranged at an upper part of each of the first and second drying chambers 1 and 2, respectively, and these sensing means 10 and 11 are cooperatively related with the first and second operating means 8 and 9. When a sensing signal of each of the sensing means 10 and 11 is generated by a control means 12, discharging holes 6, 7 arranged at the ceiling part of each of the drying chambers 1 and 2 are closed so as to restrict a flowing of hot air for each of the drying chambers 1 and 2 and to promote flow of hot air for another drying chamber.