To avoid the trouble that a lens is processed into an erroneous shape.

A method for determining processing data of a spectacle lens determines processing data including a lens shape with which a peripheral edge of a lens is to be processed by a spectacle lens peripheral edge processing device including a peripheral edge processing tool for processing a peripheral edge of a spectacle lens. The method includes: a fundamental lens shape acquisition step of acquiring a fundamental lens shape; a determination step of determining whether a lens can be processed into a fundamental lens shape by the peripheral edge processing tool or not on the basis of a diameter of the peripheral edge processing tool; and a processing lens shape determination step of, when it is determined in the determination step that the lens can be processed, determining the fundamental lens shape as lens shape data for processing for the peripheral edge processing tool.