The fungus damage which has been a problem on a corrugated board carton for export canned foods was investigated and the following results were obtained: Twelve strains of mold were identified; Contaminated molds had to germinate and grow independently on both inside and outside of cartons while transported by boat; Molds were not induced by the process of carton production; Mold spores were more dominant outside of the factory; Adhesive paste was not enough as a nutrient for mold growth; Some species of Penicillium, Aspergillus and Trichoderma grew in a broad range of temperature and humidity; and Mold growth was more remarkable on liner than medium during transportation of corrugated board.