To provide a visual inspection method of a laver and a device therefor capable of inspecting existence of a chip by simple discrimination processing, even when the laver is conveyed in the tilted attitude to an imaging means.

After performing image rotation processing of each laver image in the same direction as the conveyance direction (array direction of imaged pixels P), an inspection domain line is set on the optional pixel inside from a horizontal tangent and a vertical tangent which are outer side tangents of four sides relative to the laver image, and existence of a chip in an inspection domain enclosed by the inspection domain line is discriminated. Consequently, chip discrimination of the laver can be performed precisely over the whole peripheral portion of the laver without being influenced by an irregular shape of the laver peripheral portion, and the inspection domain line can be constituted of a simple vertical reference line or horizontal reference line along the array direction of the imaged pixels P. Hereby, chip discrimination of the laver in a wide detection range can be performed by the simple discrimination processing.