In order to make it possible for an operator of a machine tool to easily calculate machining conditions and prevent calculation errors and input errors by the operator, this control device for a machine tool, which machines a work piece on the basis of a machining program, is provided with: a database that stores calculation formulas corresponding to types of calculation, and types of parameters required to execute said calculation formulas; an input unit that selects a type of calculation; and a display unit that displays, on the basis of the type of calculation selected by the input unit, the parameter to be input.