PURPOSE: The titled composition, containing a compound, e.g. S-(4-chlorobutyl) N,N-diethylthiolcarbamate, as an active constituent, and having almost no toxicity to fishes and a selective herbicidal activity against barnyard grass.

CONSTITUTION: A thiolcarbamate herbicidal composition for paddy fields containing a compound expressed by the formula (n is an integer 2W8) as an active constituent. The resultant herbicidal composition has no anemic symptoms generally observed in the thiolcarbamate herbicides for paddy fields. The death in a large number of fishes, e.g. a carp, can be avoided due to the subacute poison in a low concentration. Thus, the composition has a very high safety and practicality.