An encryption information determination section in a communication device negotiates an encryption algorithm to be used for encrypted communications with an encryption information determination section in a network camera, which is a communication counterpart. At this time, the encryption algorithm to be selected is varied depending on the CPU load of the communication device. That is, if the CPU utilization rate is high, a low-load encryption algorithm is selected, and if the CPU utilization rate is low, a high-load encryption algorithm is selected. A encryption/decryption processing section performs code processing using the encryption algorithm selected by the encryption information determination section.