To provide a recycled product manufacturing method capable of using unnecessary wood and building waste wood as a safe building material of high quality by solving the problem wherein the unnecessary wood and the building waste wood are recycled and utilized as chips or sawdust heretofore to be generally used in agriculture or stock breeding but it is necessary to apply insecticidal and antiseptic treatment to the unnecessary wood and the building waste wood in order to use them as a building material to bring about danger because of the use of chemicals.

A component peculiar to Alpinia speciosae semen (Zingiber officinale) is combined with a recycled material being chips or sawdust of the waste wood and the building waste wood. By this method, a safe product having insecticidal, antiseptic and deodorizing effects is obtained. The Getto is Alpinia speciosa Wendl. K. Schum in the scientific name and widely distributed and cultivated from the southern part of Kyushu to Okinawa and from Taiwan to India to be easily obtained as a raw material.