<P>PROBLEM TO BE SOLVED: To provide an optical information detecting method and an optical information detector which can efficiently detect optical information stored in an optical information storage medium by using a 1:N over-sampling method (wherein N is a non-integer greater than 1). <P>SOLUTION: The optical information detecting method comprises: detecting an image of a source data page including a frame mark by use of an optical detection region smaller than a size of detection pixels within 1:N excessive detection pixels (wherein N is a non-integer greater than 1); monitoring a light intensity of the detected image and discriminating a matching state of the frame mark; discriminating the distribution regularity of valid detection pixels in the detection pixels in accordance with the discriminated matching state of the frame mark and detecting sampling detection pixels; and sampling an image of the sampling detection pixels from the detected image and reproducing the image of the source data page. <P>COPYRIGHT: (C)2007,JPO&INPIT 
OPTICAL INFORMATION DETECTING METHOD AND OPTICAL INFORMATION DETECTOR