PURPOSE: To enable gathering of SHIITAKE mushroom exclusively from the upper face of an artificial medium, by putting an artificial medium in a vertically elongated cylindrical bag made of a synthetic resin film and enhancing the ripening of the artificial medium at the upper face.

CONSTITUTION: A respiration hole 4 is bored at the center of an artificial medium 1 put into a synthetic resin bag 3. The respiration hole 4 is bored at the center of the upper part of the artificial medium 1 and has shallow depth. Air is supplied to the artificial medium 1 via the respiration hole 4 to effect gradual ripening of the artificial medium from the upper face. In the case of growing SHIITAKE mushroom 2, the synthetic resin bag is opened by cutting the upper part of the bag. The operation of gathering, etc., of the grown SHIITAKE mushroom can be easily carried out because the growth of SHIITAKE mushroom in whole artificial medium 1 is inhibited and the SHIITAKE mushroom grows exclusively at the upper face of the artificial medium.