A digital protective relay device connected to a first point of a power transmission line of an electric power system via a terminal and communicating with another digital protective relay device connected to a second point of the power transmission line via another terminal, the digital protective relay device comprising: an analog/digital conversion portion, which is configured to, after sampling a system electrical quantity signal acquired from the first point at m times, m > 12, of the fundamental frequency f0 linked to the power signal in the power transmission lines of the electronic power system thereof, perform conversion into n-bit digital data, n > 12, and obtaining m sampling data of n bits generated with sampling rate of frequency m·f0; a first data processing portion, which is configured to convert the m sampling data of n bits with frequency m·f0, obtained by the analog/digital conversion portions, into data with a frequency k·f0 (k ≤ m) at or below the frequency m·f0, and obtaining k sampling data of n bits generated with sampling rate of frequency k·f0; a transmitting portion, which is configured to transmit k sampling data obtained by the first data processing portion to the another protective relay device in a prescribed transmission format; a receiving portion, which is configured to receive k sampling data of the second point, transmitted as transmission data from the transmitting portion of the another protective relay device; a receiving processing portion, which is configured to convert k sampling data of the second point, received by the receiving portion, into data with frequency L·f0 (L ≤ k ≤ m) at or below the frequency k·f0 and obtaining L sampling data of n bits generated with sampling rate of frequency L·f0 of the second point; a second data processing portion, which is configured to convert k sampling data, obtained by the first data processing portion, into data with frequency L·f0 (L ≤ k ≤ m) at or below the frequency L·f0, and obtaining L sampling data of n bits generated with sampling rate of frequency L·f0 of the first point; and a computing processing portion, which is configured to perform differential computation between L sampling data of the second point obtained by the receiving processing portion and L sampling data of the first point obtained by the second data processing portion, and when the differential computation result is equal or greater than a prescribed value, the computing processing portion outputs a trip command an analog/digital conversion portion, which is configured to, after sampling a system electrical quantity signal acquired from the first point at m times, m > 12, of the fundamental frequency f0 linked to the power signal in the power transmission lines of the electronic power system thereof, perform conversion into n-bit digital data, n > 12, and obtaining m sampling data of n bits generated with sampling rate of frequency m·f0; a first data processing portion, which is configured to convert the m sampling data of n bits with frequency m·f0, obtained by the analog/digital conversion portions, into data with a frequency k·f0 (k ≤ m) at or below the frequency m·f0, and obtaining k sampling data of n bits generated with sampling rate of frequency k·f0; a transmitting portion, which is configured to transmit k sampling data obtained by the first data processing portion to the another protective relay device in a prescribed transmission format; a receiving portion, which is configured to receive k sampling data of the second point, transmitted as transmission data from the transmitting portion of the another protective relay device; a receiving processing portion, which is configured to convert k sampling data of the second point, received by the receiving portion, into data with frequency L·f0 (L ≤ k ≤ m) at or below the frequency k·f0 and obtaining L sampling data of n bits generated with sampling rate of frequency L·f0 of the second point; a second data processing portion, which is configured to convert k sampling data, obtained by the first data processing portion, into data with frequency L·f0 (L ≤ k ≤ m) at or below the frequency L·f0, and obtaining L sampling data of n bits generated with sampling rate of frequency L·f0 of the first point; and a computing processing portion, which is configured to perform differential computation between L sampling data of the second point obtained by the receiving processing portion and L sampling data of the first point obtained by the second data processing portion, and when the differential computation result is equal or greater than a prescribed value, the computing processing portion outputs a trip command