Abstract: With the recognition that like esterase, the thiazole derivatives show a strong nucleophilicity owing to sufficient electronic density in heterocycle, when its ester is degraded by some enzymes. The composition for detecting leucocyte and proteinase in urine has been developed, which contains a thiazole derivative. According to this invention, the thiazole derivative may be synthesized as an ester form by combining both the well-known thiazolone derivative and amino acid derivatives as starting materials. Now that the method for manufacturing the thiazole derivative is simple and general, the mass-scale production may be available within a short period of time. Further, in case of the measuring device produced according to this invention, the application method is simple and diagnostic performance is superior.