A clear spin injection was detected in the Fe/InAs hybrid system without tunneling barrier despite the contradictory predictions of the conductivity mismatch arguments. The spin-polarization was detected by measuring the circular polarization of the electroluminescent light (EL) from the cleaved edge of the InAs sample and from the top of the sample where external magnetization was utilized. By switching the angle of the quarter-wave plate, a clear difference between the sigma(+) and sigma(-) component from the EL was observed. The measured polarization of the luminescence P-L was found to be 3.6-4.1% in the case of lateral remnant magnetization. The vertically magnetized samples exhibit clear spin-polarization which alternates with magnetization direction with its maximum polarization of 12%. These results clearly indicate that the direct spin injection at the Fe/InAs junction is possible, suggesting ballistic spin-injection mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.