To provide a machine tool system where a plurality of machine tools or machining parts are arranged side by side, capable of reducing the overall breadth and attaining highly precise machining.

This machine tool system is formed by arranging the plurality of machine tools 1 in proximity or contact conditions to/with each other. The machine tool 1 is provided with a main spindle for rotating a workpiece W and a tool rest 12. The main spindle 9 is positioned so as to be orthogonal to the arranging direction of the machine tool 1. At least one of the machine tools 1 arranged is provided with a tailstock 11 disposed on a bed 8 mounting the main spindle 1. There is also provided a conveyance apparatus 80 for conveying the workpiece W between the plurality of machine tools 1.