In the title compound, C12H12ClN5O3S, the pyrazole ring and the benzene ring are approximately coplanar. The mean plane of the pyrazole ring makes a dihedral angle of 12.82 (13)° with the mean plane of the benzene ring. The crystal packing is stabilized by intramolecular N—H⋯O and intermolecular N—H⋯O and N—H⋯N hydrogen bonds.