A biometric authentication device has a structure member which is wearable to a user, and a biological information acquisition unit that acquires biological information of the user, and a biometric authentication unit that performs authentication of the user. The biological information acquisition unit is provided in a position where a finger of the user in contact when the structure member is worn/removed to/from the user, acquires first biological information with the finger of the user in contact with the biological information acquisition unit and second biological information which is at least one of a finger direction and action data, the finger direction is a direction of the finger in contact with the biological information acquisition unit and the action data is a data corresponding to spatial movement of the biometric authentication device when the structure member is worn/removed to/from the user. The biometric authentication unit performs the authentication based on the first and second biological information.