An apparatus and a method authenticates a user according to biometric information such as a fingerprint, voice, etc. A biometric information input unit inputs biometric information. An extraction unit extracts biometric information extracts biometric feature information from the input biometric information. An estimation unit estimates the matching precision of the extracted biometric feature information. A request unit requests an input of additional authentication information. An authentication information input unit inputs authentication information. A biometric feature information registration unit preliminarily stores registered biometric feature information. An authentication information registration unit preliminarily stores additional registered authentication information. A biometric feature information matching check unit has a matching check between the extracted biometric feature information and the registered biometric feature information. An authentication information matching check unit has a matching check between the input authentication information and the registered authentication information. A determination unit computes the matching precision by combining the matching check result about the biometric feature information with the matching check result about the additional authentication information, and determines based on the computation result whether or not the user is authenticated.