1. A method of authenticating an individual, wherein at least one information out of an eyeground blood vessel image information obtained by an optical means, eyeground blood flow distribution image information obtained by using a laser, and information relating to the change over time thereof is compared and collated with personal information registered in advance, the method comprising: providing a fixation screen displaying a fixation target having a plurality of fixation point candidates for fixing the direction of the line of sight, said plurality of fixation point candidates being simultaneously displayed to the individual, registering in advance one of the fixation point candidates to fixedly view on the fixation screen, and comparing and collating at least the one information out of the eyeground blood vessel image information, the eyeground blood flow distribution image information, and the information relating to the change over time thereof within a measurement field of view obtained in a direction of a line of sight registered in advance with the personal information registered in advance.