To prohibit the decryption of encrypted information in places exclusive of a specific place.

This apparatus includes a keyboard input device 17 for inputting information for forming an encryption key into which position information of a prescribed point is included, an encryption key forming means 21 for forming an encryption key from the information for forming the encryption key, a cipher forming means 22 for encrypting the information to be kept secret by using the formed encryption key, a portable wireless telephone 2 for receiving the position information of a present point from a position information notifying device, a decryption key forming means 23 for forming a decryption key by using the received position information and a decryption means 24 for decrypting the ciphertext formed by the cipher forming means 22 by using the formed decryption key.