A novel azobenzene-based photochromic amorphous molecular material, tris[4-(phenylazo)phenyl]amine (TPAPA), was designed and synthesized. TPAPA was found to readily form an amorphous glass with a glass-transition temperature of 67 degrees C and to exhibit photochromism as amorphous film. Irradiation of amorphous film of TPAPA with two coherent Ar+ laser beams led to the formation of surface relief grating with a diffraction efficiency of 2 similar to 3% and a modulation depth of ca. 100 nm.