In an embodiment, a machine tool includes two fixed modules and two movable modules each of which having a main spindle, a headstock, and a tool post being integrally formed, and a bed on which these are installed. The movable modules are provided on the bed to be movable in the Y-axis direction, the fixed modules are fixed on the bed on the opposite sides of the these movable modules, and a recess is provided next to the fixed module, the recess being formed by cutting out the bed. The movable modules are movable such that the axis lines of the main spindles of the movable modules are aligned with the axis line of the main spindle of the fixed module or the fixed module. The movable module is movable to the opposite position of the recess.