NOVELTY - The apparatus has a track unit (110) with an endlessly rotating track belt (111) to provide a user with a running or walking environment. A load sensor module is located at the belt for measuring load from a user at the front part and at the rear part of the belt. A pair of rollers (112) guides the belt at the end part, and a driving unit drives the rollers to rotate the belt. A control panel unit (120) with a control panel (121) controls the driving unit to accelerate or decelerate the speed of the belt based on the measured values of the load sensor module.    USE - Used for controlling proceeding speed of a track belt of a treadmill, corresponding with a user`s intention, where the treadmill is used indoors e.g. home or in a sports center, for allowing users to have an effect of exercising while working or running on the belt in narrow space.    ADVANTAGE - The control panel unit with the control panel controls the driving unit to accelerate or decelerate the speed of the track belt based on the measured values of the load sensor module, thus automatically controlling the proceeding speed of the track belt precisely corresponding with a user`s intention without the user`s direct operation for changing the speed of the track belt while running or walking on the treadmill, in a cost effective manner, and hence providing comfortable exercise environment while minimizing inertial force effect. The apparatus provides a stable speed change control device while avoiding drastic change of speed.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a method for controlling the speed of track belt rotation    (2) a treadmill for measuring the user`s weight.    DESCRIPTION OF DRAWING(S) - The drawing shows a structure of a treadmill.    Track unit (110)    Endlessly rotating track belt (111)    Rollers (112)    Deck (113)    Support rollers (117)    Support member (118)    Control panel unit (120)    Control panel (121)    Handle rod (122)    Connecting members (124)