NOVELTY - A micro-integrated cardiac pacemaker comprises a control unit for outputting a control signal, heart-stimulating means for stimulating a heart tissue in response to such signal, cardiogragh information-extracting means for obtaining cardiograph information for outputting to the control unit, and a power supply unit for providing drive power.    USE - The pacemakers are for use in (distributed) cardiac pacing systems, which are applicable e.g. in brachycardic patients.    ADVANTAGE - Such oxidase-based biological cell-powered pacemakers are micro-integrated, without needing lead and chest incision thereby reducing physical burden to patients.    DETAILED DESCRIPTION - A micro-integrated cardiac pacemaker comprises a control unit for outputting a control signal, heart-stimulating means for stimulating a heart tissue in response to such signal, cardiogragh information- extracting means for obtaining cardiograph information for outputting to the control unit, and a power supply unit for providing drive power. The control unit outputs a control signal according to the cardiograph information. The power supply unit is a biological fuel cell that takes out electrons by oxidation of a biological fuel, and such fuel cell is characterized in that it is consisted of an anode and a cathode together with an oxidase of a biological fuel and a mediator both immobilized onto the cathode, in which the blood and/or body fluid are employed as the electrolytic solution, and a biological fuel and oxygen in the blood and/or body are used, with the biological fuel cell attached to the end of a catheter and implanted into the heart before withdrawing such catheter and without necessitating incision on the chest.    INDEPENDENT CLAIMS are also included for:    (1) similar pacemakers in which the cardiograph information and control signal are modified for sending outside through an equipped means together with a receiving means capable of reproducing such information and signal, and optionally a means for inputting data from outside to the control unit, with all these available information and data incorporated for outputting from the control unit;    (2) cardiac pacing systems with the cardiac pacemakers for attachment to the atrial muscle with a control unit to regulate stimulation timing and a means for changing such timing based on the detected P wave information; and    (3) distributed cardiac pacing systems containing 1 or more of the cardiac pacemakers particularly in groups with control units and means for changing stimulation timing based on the detected P wave information and QRS group information especially that of the earliest stage, thereby allowing smooth operation individually or in combination to aid the heart to beat regularly.