A single-ended ring oscillation device for generating a fully differential signal is provided. The single-ended oscillation device includes a single-ended ring oscillator and a phase processing unit. The single-ended ring oscillator includes an odd number of inverting delay units. The inverting delay units sequentially generate a first signal, a second signal and a third signal. The phase processing unit generates an intermediate signal according to the first signal and the third signal, and outputs the intermediate signal and a delayed version of the second signal as a fully differential signal. The intermediate signal and the second signal are opposite to each other in phase.