A reconfigurable integrated circuit device includes plural processing elements each including an arithmetic circuit, and being configured in any computing state based on the configuration data; and an inter-processing element network which connects the processing elements in any state based on the configuration data. And the processing element inputs an input valid signal and an input data signal, and outputs an output valid signal and an output data signal, and includes an input data holding register, an arithmetic processing circuit, and an output data holding register which holds the computing result data, and when the configuration is updated by configuration data which makes a hold mode valid, regardless of the input valid signal, valid or invalid, the input data holding register holds the input data signal upon the update and the arithmetic processing circuit performs computing processing on the input data signal held in the input data holding register.