To provide an individual authentication device which can determine whether or not authentication is valid with good accuracy without damaging convenience, and to provide an authentication method by the individual authentication device.

The individual authentication device has: keyless entry systems 12, 13 which each determine whether or not authentication of an individual to be authenticated is valid, based on terminal information transmitted from a portable terminal 50; a pattern sensor 11 arranged in a doorknob 9; a pattern information storage section 17 in which registered pattern information 22 of a registrant is stored; a pattern comparing device 16 which is operable after validation of the authentication by the keyless entry systems, and determines whether or not the authentication of the individual to be authenticated is valid, based on an alignment between the authenticating pattern information of the person to be authenticated, detected by the pattern sensor 11 when the door knob 9 is gripped, and the registered pattern information 22; and a door lock control means 14 which can unlock a door lock if the authentication is determined to be valid by the pattern comparing device 16.