PURPOSE: To enable transformant yeast to mass produce surface antigen of hepatitis B virus, by forming artificially a sequence having high complementation with 3' end part of 18 ribosomal RNA.

CONSTITUTION: A yeast containing a recombinant DNA obtained by bonding DNA which is prepared by adding a sequence having complementation with 3' end part of 18 ribosomal RNA to the upper stream of DNA to code surface antigen of hepatitis B virus to just the back of a sequence having complementation with 3' end part of 18 ribosomal RNA existing in 5'-untranslated range of yeast inhibitory acidic phosphatase gene is cultivated, the surface antigen of hepatitis B virus is formed and accumulated, and it is collected.