There are electromagnetic compatibility standards for the approval of electronic devices installed on aircraft. Japanese Ministry of Defense aircraft must conform to standard NDS C 0011C, which is similar to the United States Military Standard 461F: Requirements for the control of the Electromagnetic Interference Characteristic of Subsystems and Equipment (MIL-STD-461F). The former is also often applied to emergency medical equipment used in aircraft for patient airlift. In this study, we evaluated the electromagnetic compatibility of several Holter monitor models for use in electrocardiographic measurement of pilots in Kawasaki T-4 aircraft. We used four types of antennas (a 10 kHz–30 MHz rod antenna, a 30–200 MHz biconical antenna, a 200 MHz–1 GHz log-periodic antenna, and a 1–18 GHz double-ridged horn antenna) for detection of electromagnetic waves emitted from the electrocardiograph, and we used an EMI receiver for measurement. Antennas were placed at a height of 120 cm and a distance of 100 cm distance from the electrocardiograph, which was placed on a 70-cm-tall pedestal. The Holter monitors were connected by induction electrodes and powered by a battery. The models tested were the Cardy® 203, Cardy Pico®303+, RAC-3103 Cardiomemory®, and HOLTREC®. Levels of emitted electromagnetic waves were measured five times, and the maximum obtained value was compared with MIL-STD-461F. We found that each electrocardiograph model emitted electromagnetic waves below the level specified in the military standard.