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: 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 fixed by a fixation target registered in advance with the personal information registered in advance.