A control device (100) for a machine tool, the control device (100) being provided with: an individual database (108) that stores voice data and image data for the face for each of a plurality of persons in association with the respective person's ID; an input command database (120) that stores commands that can be inputted into a machine tool; an imaging device (102) that images the face of a person; a microphone (104) that inputs a voice; and a microprocessor that processes the image data for the face imaged by the imaging device and the voice data inputted from the microphone. The microprocessor performs facial authentication on the basis of the image data of the face, and performs voice authentication on the basis of voice data inputted from the microphone. If the voice is a voice produced by a facially authenticated person, the microprocessor analyzes voice data, searches the input command database on the basis of the analysis result, and inputs a command corresponding to the voice data into the machine tool.