Since penicillin-producing organism was discovered, the research for the improvement of strain and penicillin process has been continually carried out for a period of well-over thirty years throughout the world. Due to the studing effort for enhanced penicillin production, the industrial production of penicillin increased tremendously and the penicillin price was reduced greatly. However, in our country, penicillin process technology has not been developed and the total amount of penicillin is not imported from foreign companies. Therefore, experimental studies on induction, isolation, and selection of superior penicillin-producing variants of $\mbox{\underline{penicillium}}$ $\mbox{\underline{chrysogenum}}$ were carried out in this research. A number of penicillin-producing mutants have been isolated from the survival population that are obtained by treatment of mutagenic agent, methylbis ($\beta$-chloroethyl) amine and by U.V treatment, and their penicillin productivity has been evaluated.