There is provided a shoe bottom repair agent consisting of one-component thermosetting composition comprising as main ingredients a terminal isocyanate having urethane prepolymer and/or a polyisocyanate compound and a latent curing agent. This shoe bottom repair agent is free from, experienced in use of solvent base shoe bottom repair agents, safety and sanitation problems such as odor and inflammation by solvent evaporated at the time of curing as well as cured matter thickness reduction of a mended part caused by solvent evaporation. With use of this shoe bottom repair agent, damaged shoe bottom portion can be mended to a desired shape through one-time repair work. Short-time curing can be effected by heating. Further, before heating, there is substantially no viscosity increase and no surface film is formed to avoid adhesion of a film resulting from surface drying to a spatula. Therefore, the repair surface can be finished smoothly and neatly.