Browning of catecholamines such as dopa, dopamine, noradrenaline and adrenaline with apple enzyme was estimated. In the course of the browning, the absorption spectra with the peak at 475~480 nm was formed. On the other hand, variation of UV spectrum was also estimated and the maximum increase of the optical density was determined at 300~305 nm. Enzymatic browning was observed for 3, 4-dihydroxytoluene too, whose UV spectrum is similar to those of catecholamines. However, differing from catecholamines, the absorption spectrum with the peak at 400 nm was formed during the browning.