To provide a personal authentication device which facilitates a personal authentication for a user.

The personal authentication device 10 is constituted of an authentication receiving part 20 connected to an authentication main unit 30 requiring personal authentication, and an authentication transmitting part 11 composed as a separate body from the authentication receiving part and to be worn on a part of user's body. The authentication transmitting part 11 includes an input part 12 to input personal authentication information and a transmitting means 15 to transmit the personal authentication information inputted from the input part to the authentication receiving part, and the authentication receiving part 20 includes a receiving means 21 to receive the personal authentication information transmitted from the authentication transmitting part and an output part 23 to send out the received personal authentication information by the receiving means to the authentication main unit.