The study was carried out on the biochemical characters of Cd-BP(I) after isolation and purification of the protein from the liver of rat injected intraperitoneally with Cd. A c ontinued study has been doing whether Cd-BP(I) could be induced by Cd or by other metals such as Zn and Cu. Antisera were made against the Cd-BP(I) from NewZealand white rabbits. Carried out were ${gamma}$-globulin purification, then Ouchterlony test adn gel immunodiffusion test. Cd-BP(I) was also found in normal tissues of rat. It was induced up to a considerable level by Cd, whose induced level was higher than that of Cu or Zn treatment. The level of induction by Cu or Zn pretreatment plus Cd treatment was lower than that by simple treatment of Cu or Zn. Such a result was presumably related to the Cd toxicity.