Queen-produced pheromones have long been believed to influence the behaviour and physiology of colony members. Recently, a queen-produced volatile chemical consisting of n-butyl-n-butyrate (nBnB) and 2-methyl 1-butanol (2M1B) was identified as a termite queen pheromone that inhibits the differentiation of new neotenic reproductives in a subterranean termite Reticulitermes speratus (Matsuura et al. 2010, PNAS). In addition, the same volatile chemical is emitted by eggs themselves and plays a role both as a worker attractant and inhibitor of reproductive differentiation. Here, we report that the volatile compounds of the termite queen pheromone have antifungal function. We found that both of the chemicals significantly suppress mycelial growth of a various fungi including termite ball fungus, which is a termite nest parasite mimicking termite eggs. Interestingly, the antifungal activity of nBnB and 2M1M differed significantly among TMB strains originated from different nests. We discuss the evolutionary process of the termite queen pheromone from the viewpoint of semiochemical parsimony.