The method for producing functional compost according to the invention includes: inoculating a filamentous fungus with a function, such as the Coprinus curtus GM-21 strain (NITE BP-37) with a plant disease control function, into compost in an bacterial-activity-restricted state which is, for example, at least one state selected from the group consisting of a nutrient-restricted state, a pH-restricted state and a water content-restricted state; and cultivating the filamentous fungus in the compost to allow its selective proliferation. Further, the invention provides functional compost obtained by the above production method, as well as compost for proliferating a filamentous fungus in a bacterial-activity-restricted state.