The present invention addresses the problem of enhancing the fluidity of a polybutylene terephthalate resin composition that uses a halogenated benzyl acrylate-based flame retardant as a flame retardant while maintaining properties such as excellent mechanical strength that a polybutylene terephthalate-based resin possesses. The problem is solved by adding a protic compound to the polybutylene terephthalate resin composition that uses a halogenated benzyl acrylate-based flame retardant as a flame retardant.