Laves phase intermetallic compound, catalyst using intermetallic compound, and method for producing ammonia

Provided are: a laves phase intermetallic compound having a composition represented by general formula ARu 2 (A is Y, Sc, or at least one type of element selected from lanthanoid elements excluding Ce), the crystallite size thereof being 1 nm to 100 nm; a catalyst including the intermetallic compound as an active ingredient; and a method for producing ammonia using the same.