An information processing apparatus causes an encryption key data generating section to generate key data stored in a semiconductor memory by using encryption key source data read from the semiconductor memory and cipher generation data stored therein, and stores the key data in a temporary storage section. The information processing apparatus transmits data encrypted by an encryption circuit by using the key data. Upon receipt of the encrypted data, the semiconductor memory executes a command decrypted by a decryption circuit similarly using the key data. This achieves data communication only between the predetermined semiconductor memory and the information processing apparatus.