To provide a device that easily judges that content that has been edited and moved back differs from original content. A content transmission device 60 divides edited content composed of partial original content and partial edited content to generate transfer data pieces, generates a nonce value of each piece, encrypts the piece based on the nonce value, and transmits the encrypted transfer data pieces and nonce values. When switch occurs between the partial contents, the device 60 generates nonce value such that discontinuity exists between the generated nonce value and immediately previously generated nonce value. A content reception device 70 receives the encrypted transfer data pieces and nonce values, decrypts the pieces based on the nonce values, writes the transfer data pieces into recording medium. When discontinuity exists between currently received nonce value and immediately previously received nonce value, the device 70 detects reception of partial edited content.