PURPOSE: To improve polishing efficiency by providing a driving means for oscillating a tank for storing an abrasive and a material to be polished in a reciprocating manner, around a horizontal axis, as well as a shot device for ejecting the abrasive from the upper opening of the tank into the tank.

CONSTITUTION: An abrasive and a material to be polished are charged into a tank 8 when dry polishing is to be carried out, and further, the water is added therto when wet polishing is to be carried out. When a driving motor 31 is driven, a cylindrical cam 35 is rotated, and a reciprocating member 41 is reciprocated along a slide guide 40, and since a rack 45 is reciprocated, a pinion 28 engaged with the rack is reciprocally rotated, while an oscillating frame 5 is reciprocation-oscillated through a supporting axis 2a, an oscillating arm 3a, and a vibrationproofing rubber 4, and the tank 8 is reciprocation- oscillated through a spring 7. A driving motor 22 which can be freely rotated inward is rotated at high speed by a shot device 21, and the abrasive supplied to the center part of an impeller is accelerated by a vane, while the abrasive is equally ejected into the oscillating tank 8. The abrasive effectively collides with the material to be polished in the tank, and polishing efficiency is thus improved.