A steel sheet inspection device 1 according to the present invention includes a magnetooptic element 5 that converts a magnetic domain structure of a steel sheet "S" to be inspected to an optical property that is detectable as the optical property, a light source 7 that irradiates the magnetooptic element 5 with linearly polarized light, a detector 12 that detects the linearly polarized light with a polarization plane rotated according to the magnetic domain structure of the steel sheet "S" transferred to the magnetooptic element 5, and a drive mechanism that drives at least the magnetooptic element 5 so as to contact and separate the steel sheet "S" and the magnetooptic element 5 with and from each other. Thereby, by visualizing and inspecting the magnetic domain structure of the steel sheet immediately after a magnetic domain refining process, the yield is able to be improved.
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