To provide a machining simulation device enabling an operator to fully recognize a tool feed operation even when performing magnified and reduced plotting and having shortened time required for the operation confirmation of the tool feed operation.

Stock shape data D1 from a stock shape data storage means 4, plotting range data D2 from a plotting range data storage means 5 and feed speed data F from a feed speed data storage means 1 are read to a feed speed correction means 6. Feed speed correction data Fa corrected on the basis of the stock shape data D1, the plotting range data D2 and the feed speed data F are prepared in a feed speed correction means 6, the feed speed correction data Fa are read to a plotting means 2 and the tool feed operation is plotted on a screen.