PURPOSE: To prevent a lens from being displaced from the grinding region of a grinding wheel.

CONSTITUTION: A lens grinding device is provided with a lens shape measuring device 100 to measure a distance from a reference position to the peripheral edge of the surface of a lens R2 in the direction (a direction X) of the thickness of the lens and a distance therefrom to the peripheral edge of the target grinding shape of the surface of a lens R1, and a data memory 83 to store the maximum value XTMAX and a minimum value XTMIN of a distance in the direction X of the grinding region of a grinding wheel 3a measured on the basis of a reference position. Further, the lens grinding device is provided with a program memory 82 in which is registered a program which determines the maximum value XMAX and the minimum value XMIN among distances related to a lens measured by the lens shape measuring device 100 and which sets the position of the lens in a direction X within a grinding allowable range where a position for indicating the maximum value XMAX is below the maximum value XTMAX related to the grinding wheel 3a and a position indicating the minimum value XMIN related to a lens exceeds the minimum valve XTMIN related to the grinding wheel, and a CPU 81 to execute the program.