PROBLEM TO BE SOLVED: To provide an antifungal agent composition for a building material, giving fungus resistance maintained without reduction for a long term to a building material to be arranged under wet conditions such as water-area or a raw material and the like thereof, even when compounded in a less amount.SOLUTION: An antifungal agent composition for a building material contains a hindered amine-based compound having a structural part represented by the formula (1) and a structural part represented by the general formula (2) (Ris a hydrogen atom or the like) in a molecular skeleton thereof and at least one kind antifungal agent selected from the group consisting of triazole-based antifungal agents, imidazole-based antifungal agents, benzimidazole-based antifungal agents and fludioxonil.
