To give antibacterial mildewproofing properties to obtained expandable organisms by handling beads before molding of granules of uniform shape without processing in response to the special shape of each molding or preliminarily expanded beads as fluid and giving antibacterial mildewroofing properties continuously and in a large amount by a simple apparatus.

Thermoplastic resin expanded beads or preliminarily expanded beads are mixed with an aqueous a/o oily paste in which a compound of an antibacterial metal such as silver, copper, and zinc is dispersed, it is packed in a foaming mold, or is dried while being dispersed in dry cold air to prevent the aggregation of the beads to make antibacterial expanded beads, which are packed in the foaming mold to obtain an antibacterial mildewproofing molding by heating. Although it does not respond to a special shape of each molding, antibacterial mildewproofing properties are given not only to the whole surface of the molding but also to the gaps between the beads left after molding, numbers of apparatuses, facilities, and man days associated with after processing are made unnecessary to be attained by fitting light, fine parts.