PROBLEM TO BE SOLVED: To provide a digital protection and control device that facilitates the expansion or the consolidation of functions. SOLUTION: The digital protection and control device includes protection computing means 1a that carries out main detection processing, based on a system signal 1l fetched via an input converter 1k; digital input/output means 1b on the main detection side; protection computing means 1d that carries out outage detection computation processing; and digital input/output means 1e on the outage detection side. Furthermore, the means 1a, 1c and 1d are provided with a common memory 100. Each element is provided with a communication controller, and all the elements are connected together, through a serial bus 3a constituted of fixed-frequency protocol communication means. Since the serial bus 3 is provided with a bus master function, with which all the elements can acquire the bus right and the elements carry out data transmission among them at a fixed frequency, real-time protection and control can be achieved. COPYRIGHT: (C)2007,JPO&INPIT