To provide a substrate tester and a test condition setting method capable of selecting a test condition suited to a substrate even when surface pattern information of the substrate is unobtainable in advance.

The substrate tester 50 includes an elevation calculation part 304 calculating one or more elevations between an optical axis of an irradiating part 2 or an imaging part 6 and a normal line of the substrate 1 that enables to image diffraction light for all inspectable pitches of pattern on the substrate 1; and an azimuthal angle setting part 301 searching a rotation angle from a reference location of the substrate 1 in which brightness of the image satisfies a predetermined condition and selecting and setting an inspecting azimuthal angle among them based on the image of the substrate 1 taken by the imaging part 6 by rotating an rotating stage 100 under a condition that the irradiating part 2 and the imaging part 6 are fixed to all of the azimuthal angles calculated by the elevation calculation part 304.