We report on the first demonstration of pulsed regime of Raman laser based on a multimode graded-index fiber directly pumped by a CW multimode laser diode. Proof-of-principle experiments have been performed with a 3.7-km multimode graded-index fiber with 62.5-μm core pumped by 976-nm high-power laser diode and cavity formed by bulk mirror and fiber Bragg grating with intra-cavity acousto-optic modulator providing Q-switching or mode locking. At 27.2-kHz repetition rate corresponding to the laser cavity round-trip frequency (i.e. in mode-locking regime), stable nanosecond pulses with peak power of ∼300 W have been observed both at the 1st (1018 nm) and 2nd (1064 nm) Stokes orders. At that, the beam quality of generated pulses is greatly improved as compared to that for the pump diode (M2>20) reaching M2=2 for the 2nd-order Stokes wave.