The simultaneous observations of the dynamic behavior of proton and electron auroras were carried out from March to October 1970 at Syowa station (corrected geomagnetic latitude, -66.7¿; longitude, 72.5¿) in Antarctica. The hydrogen Balmer beta (H&bgr;) was selected as a typical emission line from proton auroras, whereas N2+ 4278-¿, and O I 5577-¿, and O I 6300-¿ emissions were selected for electron auroras. The H&bgr; photometer has a tilting filter to measure rapid space-time variations of faint proton auroras free from the contamination of strong electron auroras, whereas the other photometers have fixed interference filters. By means of the records of these meridian-scanning photometers the developing features of the proton and electron auroral substorms are investigated in detail. It is found that during the period preceding the onset of a substorm expansion phase the emission zone of the proton aurora moves equatorward with a speed of 100--250 m/s, accompanying the development of the ring current. It is also found that at the onset of the expansion phase the quiet arcs suddenly brighten generally in the permidnight region and the electron auroral bulge rapidly expands poleward and westward. In the postmidnight region it is observed that the emission zone of proton auroras rapidly expands poleward with a large increase in luminosity. Proton auroras are absent in the leading edge of the expanding electron auroral bulge, whereas breakup-type electron auroras (arcs of bands) are not observed in the expanding proton auroral bulge. Therefore it is suggested that there is a mechanism that accelerates electrons in the premidnight region and protons in the postmidnight region along the geomagnetic field lines down to the ionosphere. After the onset of the expansion phase the luminosity of the proton aurora greatly increases in the evening region, and simultaneously, the emission zone expands equatorward, accompanying the development of the asymmetric partial ring current and the positive bay in this local time region. This relation indicates that the source of the proton aurora in the evening region is the injected ring current protons.