There is provided a signature generation device capable of preventing a transcript attack for signature data. The signature generation device performing signature by using a signature key stores the signature key and uses the signature key to perform signature on data to be signed, thereby generating signature data. When generating the signature data, the signature generation device counts the number of times signature has been performed by using the signature key and judges whether the counted number of times has reached a predetermined number of times. When it is judged that the counted number of times has reached the predetermined number of times, signature by using the signature key is suppressed hereafter.