P-toluic acid producing method

Provided is a method for producing a highly pure p-toluic acid by a simple liquid-solid separation operation, using as raw material a substance which is suitable to fermentation production by microorganisms and which can be derived from biomass resources. Said method for producing a p-toluic acid comprises: a dehydration reaction process in which compounds (1) - (4), which are substances suitable to fermentation production by microorganisms and which can be derived from biomass resources, are dehydrated; and a liquid-solid separation process in which a solid body generated by the dehydration reaction is collected using a simple liquid-solid separation operation.