Distortions, wherein a recording image is inclined relative to a printing plate, are removed when image data from a computer are recorded spirally in recording bands, having a predetermined band width, of a plurality of picture elements on the printing plate which is wound on a drum. Printing plate exposure apparatus comprises the printing plate being wound spirally on the drum such that an extension line of a side edge line of the printing plate is shifted a band width after one drum revolution. The printing plate exposure apparatus further includes: an exposure unit for recording the image data in the recording bands on the printing plate; a moving mechanism for moving the exposure unit by one band width along a drum axial direction relative to the drum during one revolution of the drum; and a timing mechanism for adjusting a band recording start position of the image data for each rotation of the drum so as to set a top edge line of the recording image parallel to a top edge line of the printing plate.