A control device which controls a machine tool so as to move a table during exchange of tools includes: a movement distance acquisition unit which acquires a movement distance of the table during tool exchange; a movement time calculation unit which calculates a fastest movement time from an acquired movement distance, and a speed at which the table is caused to move fastest; a tool exchange time calculation unit which calculates a tool exchange time; a comparison unit which compares the tool exchange time calculated with the fastest movement time calculated; and a speed changing unit which changes the movement speed of the table, in a case of the fastest movement time being shorter than the tool exchange time, so that the movement time of the table becomes longer than the fastest movement time.

A numerical controller with a multi-core processor estimates moving instruction creation processing time required for creation of a moving instruction that is to be executed in a predetermined cycle on the basis of a machining instruction obtained from a machining program and divides a process for creating the moving instruction with respect to cores of the multi-core processor on the basis of the estimated processing time. Consequently, processing performance for the moving instruction creation process is improved.