This report includes a summarized version of a design standard proposed by the Research Committee on Standards for Criticality Alarm Systems, which was organized in the Atomic Energy Society of Japan in October, 1973 and which terminated its activities in March, 1975. Some additional information on criticality alarm systems are included, such as the basic characteristics of criticality accidents, examples of criticality alarm systems installed in Japanese, as well as in some foreign nuclear fuel facilities, functional checks and tests of criticality alarm systems, and a survey of relevant standards already proposed and used in U.S.A., U.K. and other countries. The proposed standard incorporates reliability considerations and a criticality accident to be assumed in designing criticality alarm systems.