Method for manufacturing resin sheet which makes it possible to easily and highly efficiently obtain a resin sheet while suppressing the occurrence of cutting marks even when a thick workpiece is used

The invention provides a method for manufacturing resin sheet at high efficiency and simple manner. The method still suppresses the occurrence of cutting marks even if a workpiece having thicker thickness is used. The method for manufacturing resin sheet according to the embodiment of the invention includes the following steps of stacking a plurality of resin sheets to form a workpiece; and cutting the outer peripheral surface of the workpiece through an end mill. The cutting performed with the end mill is performed while applying an ultrasonic vibration toward the up and down directions of the end mill. According to one embodiment of the present invention, the vibration frequency of the ultrasonic vibration is 30kHz~50kHz. In one embodiment of the present invention, the amplitude of the ultrasonic vibration is 0.5[mu]m~30[mu]m. The helix angle of the end mill is under 65 degrees. The thickness of the workpiece is more than 5mm. The resin sheet is a laminated body. In addition, the resin sheet includes an opt