To provide a method and device of adjusting a slice thickness preventing damage on the surface of the sliced meat and eliminating impairment of the meat quality in a swinging type meat slicer.

This swinging type meat slicer supports a holder of a block meat swingably around a swinging center O, is provided with a butting plate 15 having an arc shape along an arc track drawn by the tip of the holder 10 by the swinging of the holder, adjacent to the tip of the holder, determines the slice thickness by receiving the tip of the block meat projected from the holer by the butting plate, swings the holder and slices the block meat by a cutter 21 provided adjacent to the tip part of the holder. When the slice thickness of the meat slicer is adjusted by moving the butting plate obliquely to tip of the cutter, the butting plate is positioned along a virtual arc around the swinging center of the holder.