the invention , disclosing a light - path device of curved - surface mirror , is a light - path device that is designed in an optical scanner . by an appropriate arrangement of the inter - relationship between the curved - surface mirror and the light - path module in its light - path route , the length of the light - path route may thereby be adjusted , such that there are different lengths of light - path route according to the different positions where the curved - surface mirror is located without the limitations of the size of the scanned object or the physics characteristics of the photoelectric conversion device itself . the invention includes curved - surface mirror , light source , light - path module , light - focusing device , and photoelectric conversion device . the light - path module further includes reflection device and light - focusing device . the reflection device is constituted of plural reflection mirrors . the light - focusing device is lens . the curved - surface mirror is belonged to a curved - surface mirror of convex type or concave type .