The present invention provides a method and a composition for restoring pollen fertility by suppressing formation insufficiency in a pollen formation process due to a high-temperature or low-temperature stress. The present invention provides a fertility restorative agent comprising an auxin as an active ingredient, and a method for restoring the fertility of a plants of the family Poaceae, comprising spreading an auxin. Moreover, the present invention provides a fertility restorative agent containing as an active ingredient a substance which inhibits auxin action, and a method for restoring the fertility of rice plant, including spreading a substance which inhibits auxin action. Preferably, the auxin is 10−4 M to 10−7 M of indole-3-acetic acid (IAA), 4-chloroindoleacetic acid, phenylacetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), α-naphthaleneacetic acid (NAA), 2,6-dichlorobenzoic acid, indolebutyric acid (IBA), 4-chlorophenoxyacetic acid, ethyl 5-chloroindazoleacetate, naphthoxyacetic acid or 2,4,5-trichlorophenoxyacetic acid.
