In an optical recording medium comprising an organic dye base recording layer and a reflective layer on a resin substrate having a groove of 1,100 to 2,300 .ANG. deep formed in one surface thereof, signals are written by directing recording light to the recording layer within the groove from the back side of the substrate at a relative linear velocity of at least 3.6 m/s whereby record marks are formed in the recording layer as a result of partial decomposition of the dye while deforming the groove bottom surface. The deformation of the groove bottom surface is minimized to less than 18% of the groove depth. The medium requires a short time for recording and offers reduced jitter on reproduction.