This study deals with the larval stages of Benizuwai-gani, Chionoecetes japonicus, and with the comparison of those between C. japonicus and Zuwai-gani, C. opilio. There are two zoeae and one megalopa. The larval stages of C. japonicus are morphologically similar to those of C. opilio excepting some characters as follows: 1) Chromatophores of zoeae and megalopa are vermillion or crimson in C. japonicus and brown or reddish in C. opilio. 2) C. japonicus is generally bigger than C. opilio in zoeae and megalopa. 3) Length of postero-lateral spine on 3rd abdominal segment is more than 1. 3 times the length of the 4th abdominal segment in C. japonicus, but is shorter than (rarely equal to) that in C. opilio. 4) Ischiopodite of cheliped has no spine in C. japonicus, but it has spine in C. opilio, in megalopa.