To enable the optimal control of a distance between opposing surfaces by detecting the distance variation in the cross direction and the distance to only the needle cloth of a cylinder by a simple method.

A cylinder 4 having a needle cloth is cooperated with the opposite-side surface, for example, a covering member and/or a flat having a needle cloth; at least one fixed sensor is placed; and a controlling means which can change the distance in radial direction between the needle cloth of the cylinder 4 and an opposite-side member 27' or 27" is placed on the opposite-side member. For example, in an apparatus for measuring a distance between opposing surfaces, placed on a spinning preparation machine such as a card or a clearer, a sensor 19 opposes the needle cloth of a cylinder 4, the sensor is placed on the opposite-side member 27' (27"), and the apparatus is constructed in such a manner that the distance to the needle cloth of the rotary body is detectable.