The authors investigated moisture content of wood at a temple, Heirinji temple, in Niigata prefecture, and at three shrines-Ichinoya, Ichinoya Yasaka and Suwa shrines-in Ibaragi prefecture, and also identified the genus of mold at the latter three shrines. In general, the moisture content of floor posts varied with the distance from the surface of the foundation stone. The lowest moisture was observed at 50 centimeters apart from the bottom of the floor post. The highest moisture content was about 40% for both the floor post and the foundation. Sixteen genera of molds were identified after isolating fungi collected from the surface of wood by the Scotch tape method, and it was observed that a moisture content which exceeds considerably the fiber-saturation point of wood enhances the development of wood-rotting fungi. The growth of fungi was retarded in wood with 25 to 35% moisture content and completely inhibited when the moisture content was below 20%.