From the bioassay-directed fractionation and isolation of dichloromethane fraction of Aquilaria agallocha, four compounds having MAO inhibitory effect were isolated by repeated silica gel column chromatography. Their chemical structures were established as psoralen (1), bergapten (2), ${alpha}-amyrin;acetate$ (3) and 5-hydroxymethylfurfural (4) on the basis of their physicochemical and spectral data. Among these compounds, psoralen and bergapten showed high inhibitory activities in vitro against mouse brain MAO with $IC_{50}$ values $21.3;{mu}M;and;13.8;{mu}M$, respectively.