The purpose of the present invention is to provide a mesoionic compound or a salt thereof that exhibits excellent control activity against various pests. Provided is a mesoionic compound represented by formula (1). (In the formula Ra represents a hydrogen atom or a methyl group R represents a phenyl group or pyridyl group which is optionally substituted with up to two substituents selected independently from R and R represents a hydrogen atom a fluorine atom a chlorine atom a bromine atom a methyl group an ethyl group an n propyl group an i propyl group a c propyl group an n butyl group an i butyl group an s butyl group a t butyl group a fluoromethyl group a difluoromethyl group a trifluoromethyl group a methyloxy group an ethyloxy group an n propyloxy group an i propyloxy group a c propyloxy group an n butyloxy group an i butyloxy group a s butyloxy group a t butyloxy group an n pentyloxy group a trifluoromethyloxy group a 2 2 2 trifluoroethyloxy group a methylthio group a methylsulfoxy group a methylsulfonyl group a vinyl group an ethynyl group etc.)
