PURPOSE: To provide a novel compd. having growth control action of undesirable plants as a herbicide.

CONSTITUTION: The ester of formula I (R1 is carboxy, cyano, formula II (R2 is 1 to 8C alkyl), the ester of formula II (R2 is 1 to 8C alkyl), the amide. of formula III (R3, R4 are pyrrolydinyl together with the nitrogen of an amide group, etc.); for example, N.n.butylthioparaconic acid amide. This compd. is obtd. by bringing the compd. of formula IV into reaction with the compd. of pCl5. The herbicide compsn. consisting of the compd. of the formula I as an active component contains the surfactant of the amt. effective to prevent the crystallization of the active component.