This invention provided a work cutting device (10) and a work cutting method capable of stably and accurately cutting a work (66) by a simple structure. In the work cutting device (10), the work (66)is disposed by a layout part (59) so as to be cut off by an inner periphery cutter blade (32). The slide table (54) of a moving part (53) supporting the layout part (59) is movably towed by a fallingweight (70) to feed the work (66) to the rotating inner periphery cutter blade (32). A projected part (56) formed on the bottom face of the slide table (54) of the moving part (53) and the control plate (82) of a speed suppressing means (76) are moved in the direction (of arrow B) of a feed stopper (84) while coming into contact with each other. The moving speed of the control plate (82) is slowerthan the moving speed of the slide table (54) by the towing of the weight (70), and the slide table (54) feeds the work (66) to the inner periphery cutter blade (32) while its moving speed is suppressed until the work (66) is brought into contact with the edge (32b) of the inner periphery cutter blade (32).