Tyrosinase, a key enzyme for melanin biosynthesis, was purified from cultured human melanoma cells by solubilization, ion-exchange chromatography, Con-A Sepharose chromatography, and hydroxylapatite chromatography. Con-A Sepharose chromatography was effective for human tyrosinase purification. Specific activity was increased 69 times and the activity yield was 40.4%. The molecular weights of purified isozymes were approximately 64,000, 62,000, 58,000, and 57,000 daltons. $K_m$ values of L-dopa and L-tyrosine were 0.4 mM and 0.2 mM, respectively. Human tyrosinase exhibited kinetic properties of lag time, substrate inhibition, and requirement of L-dopa as a cofactor for hydroxylase activity. Phenylthiourea and arbutin showed noncompetitive and competitive inhibition, respectively.