The measurement apparatus includes an outer cylinder, a shaft body longitudinally movable on the inner surface side of the outer cylinder, a plurality of bearing balls disposed between an inner surface of the outer cylinder and an outer surface of the shaft body, and a measurement part that measures a relative position between the outer cylinder and the shaft body, and a first density of the bearing balls in a first area having a first length shorter than a total length of the outer cylinder in a longitudinal direction from one end of the outer cylinder is larger than a second density of the bearing balls in a second area having a second length shorter than the total length of the outer cylinder centered on a center position in the longitudinal direction of the outer cylinder.