An apparatus for determining the center of gravity of a vehicle to be measured being applied to a truck scale including load cells (13A-13D) provided individually at around four corners of a measuring table below a bottom surface thereof, the measuring table being provided with a flat surface having a surface area on which all wheels (51A-51D) of a vehicle to be measured can be simultaneously placed and a front wheel platform located at a position in a frontal part of the flat surface and raised to a specific height, the truck scale being configured to be able to measure the weight of the vehicle to be measured by a central processing unit on the basis of measurement values fed from the individual load cells (13A-13D) when the vehicle to be measured is placed on the measuring table, the apparatus comprising: a wheel position detector for detecting a front wheel position and a rear wheel position of the vehicle to be measured that is placed on the measuring table; longitudinal displacement calculation means for calculating how much the vehicle to be measured is displaced frontward or rearward from a reference position along a front/rear direction on the basis of information on the wheel positions detected by the wheel position detector under conditions where the vehicle to be measured is placed on the measuring table; longitudinal center-of-gravity position calculation means for acquiring a front axle load and a rear axle load of the vehicle to be measured and calculating a position where the center of gravity (G or G') of the vehicle is located along the front/rear direction thereof on the basis of the front axle load, the rear axle load and the amount of longitudinal displacement calculated by the longitudinal displacement calculation means; storage means for storing information on the center of gravity along the front/rear direction calculated by the longitudinal center-of-gravity position calculation means; longitudinal center-of-gravity displacement calculation means for calculating the amount of displacement of the center of gravity along the front/rear direction by comparing information on the center of gravity along the front/rear direction newly calculated by the longitudinal center-of-gravity position calculation means under conditions where front wheels (51A, 51B) of the vehicle to be measured ride on the front wheel platform and the information on the center of gravity on the flat surface stored in the storage means; and vehicle center-of-gravity height calculation means for acquiring a longitudinal inclination angle (θ) of the vehicle to be measured under conditions where the front wheels (51A, 51B) of the vehicle to be measured ride on the front wheel platform and calculating the height of the center of gravity of the vehicle to be measured on the basis of the amount of displacement of the center of gravity along the front/rear direction calculated by the longitudinal center-of-gravity displacement calculation means and the longitudinal inclination angle (θ). a wheel position detector for detecting a front wheel position and a rear wheel position of the vehicle to be measured that is placed on the measuring table; longitudinal displacement calculation means for calculating how much the vehicle to be measured is displaced frontward or rearward from a reference position along a front/rear direction on the basis of information on the wheel positions detected by the wheel position detector under conditions where the vehicle to be measured is placed on the measuring table; longitudinal center-of-gravity position calculation means for acquiring a front axle load and a rear axle load of the vehicle to be measured and calculating a position where the center of gravity (G or G') of the vehicle is located along the front/rear direction thereof on the basis of the front axle load, the rear axle load and the amount of longitudinal displacement calculated by the longitudinal displacement calculation means; storage means for storing information on the center of gravity along the front/rear direction calculated by the longitudinal center-of-gravity position calculation means; longitudinal center-of-gravity displacement calculation means for calculating the amount of displacement of the center of gravity along the front/rear direction by comparing information on the center of gravity along the front/rear direction newly calculated by the longitudinal center-of-gravity position calculation means under conditions where front wheels (51A, 51B) of the vehicle to be measured ride on the front wheel platform and the information on the center of gravity on the flat surface stored in the storage means; and vehicle center-of-gravity height calculation means for acquiring a longitudinal inclination angle (θ) of the vehicle to be measured under conditions where the front wheels (51A, 51B) of the vehicle to be measured ride on the front wheel platform and calculating the height of the center of gravity of the vehicle to be measured on the basis of the amount of displacement of the center of gravity along the front/rear direction calculated by the longitudinal center-of-gravity displacement calculation means and the longitudinal inclination angle (θ).