A current-injected silicon-based light-emitting device was fabricated on silicon-on-insulator (SOI) by embedding Ge self-assembled quantum dots into a silicon microdisk resonator with p-i-n junction for current-injection. Room-temperature resonant electroluminescence (EL) from Ge self-assembled quantum dots in the microdisk was successfully observed under current injection, and observed EL peaks corresponding to the whispering gallery modes (WGMs) supported by the microdisk resonator were well identified by means of numerical simulations.