A minimum five-axis machine tool (11) has first to third linear feed axes orthogonal to each other as well as first and second rotational feed axes orthogonal to each other, wherein a rotational axis line of the first rotational feed axis C is parallel to the first linear feed axis Z. While a tool T and a work W are moved relatively through the second and third linear feed axes X, Y to perform machining of the work W by means of the tool T, the machine tool controls the first rotational feed axis C such that a rotational axis line of the second rotational feed axis A is perpendicular to the direction of relative movement of the perpendicular to the direction of relative movement of the tool T to the work W, and controls a power supplied to a motor for the second rotational feed axis A when a torque around the second rotational feed axis A exceeds a specified threshold.