JSME code on Fitness-for-Service for nuclear power plants defines allowable flaws for Class 1 vessels and piping in the Acceptance Standards. When the size of a detected flaw during in-service inspection does not exceed the size given by the Acceptance Standards, the flaw is accepted for continuing service without any analytical procedures. When a detected flaw is a subsurface flaw located near component surface, the subsurface flaw is transformed into a surface flaw. This paper describes the inconsistency of the subsurface transforming to surface flaw in the Acceptance Standards. Authors have developed an improving method and propose revised subsurface flaws for the Class 1 vessels and piping in the Acceptance Standards of the JSME Code.