When a user transmits data from a PC to the outside, log information can be accumulated in a composite machine connected via network to the PC and an unnecessary data outflow due to the data transmission can be prevented. In the PC, a transmission acceptance portion accepts from a user an operation for transmitting data to the outside of network and a data transfer portion transfers outside transmission data defined as a transmission target by the transmission acceptance portion to the composite machine via the network without transmitting directly to the outside. In the image forming apparatus (composite machine, etc.), a data reception portion receives the outside transmission data transmitted from the PC via the network, which are transmitted to the outside by a data transmission portion, and a log accumulation portion accumulates log information of the outside transmission data.