We demonstrate an optical parametric oscillator pumped at a repetition rate of 100 kHz by a burst-mode Yb-doped fiber laser. Pulse energies of 1.5 µJ were generated with five 4.8-µJ pump pulses. Pulse-to-pulse fluctuations could be suppressed even when only five pump pulses were used. The measured pulse length was 190 fs, which was considerably shorter than the 350-fs pump pulse length. The burst-mode operation is an easy and powerful way to increase the pulse energies of optical parametric oscillators pumped with femtosecond pulses.