PURPOSE: To easily measure the refractive power of each lens as two-dimensional distribution, by forming a moire stripe by irradiating two grid like screens with diffused light while measuring the displacement angle of this moire stripe and the original moire stripe through a lens to be inspected.

CONSTITUTION: Lattice like screens G1, G2 provided with a large number of grids each having a minimum width P are arranged in a superposed state so as to leave a small gap S therebetween and a lens L to be inspected is arranged on the rear grid like screen G2. In this case, the grid like screens G1, G2 are irradiated with diffused light from the back side thereof and a moire stripe appearing to the lens L to be inspected is observed at a position separated only over a distance l from the grid like screen G2. From the inclination of the moire stripe appearing to the lens L to be inspected when said lens L is arranged to the front surface of the grid like screen G2 to a base line and the inclination of the original moire stripe to the base line, the displacement angle of both moire stripes rotating and displacing by the lens L to be inspected is calculated and the refractive power of the lens L to be inspected is calculated on the basis of said displacement angle.