A ball screw with tilt detector includes a screw rod, two screw nuts, a channel, a plurality of balls, and a tilt detector. The screw rod is extended along a direction of an axis. The two screw nuts are installed on the screw rod and capable of moving along the axis. The tilt detector is disposed between the two screw nuts to detect a tilt angle and a preload of the two screw nuts. The tilt detector includes a force receiving element, at least one first strain sensor, and at least one second strain sensor. The force receiving element includes a point symmetric ring-type structure, and the ring-type structure has two planes which are parallel to each other and respectively contact the two screw nuts.