To provide a perpendicular guide implement having a simple structure and allowing easy visual inspection.

A perpendicular guide implement is used to check whether or not a specified part of a device or a tool is directed perpendicular to a flat object surface and consists of a beam light irradiation device fixed to the device or tool to be checked in such a way that beam light is applied in parallel with the direction in which the specified part of the device or tool is directed and a reflector plate consisting of a mirror, formed in such a way that the back surface side of the mirror is brought into contact with the object surface and the object surface and the reflector surface become in parallel, and a transparent plate arranged on the reflector surface side of the mirror. The transparent plate diffuses and reflects a part of the beam light at least on its surface and transmits a part of the beam light.