A drive control apparatus for an electric car as can correct a synchronizing frequency without employing beacons, is proposed. A wheel-diameter correction information output means includes wheel-diameter information calculation means for calculating wheel-diameter calculation information expressive of a wheel diameter of an electric car, on the basis of two-phase current information. The wheel-diameter correction information output means also includes selection output means. The selection output means selects a wheel-diameter data output WD1, the wheel-diameter calculation information WD2 based on the wheel-diameter calculation means, or wheel-diameter default information WD0, and it outputs wheel-diameter correction information WD. A synchronizing-frequency calculation means outputs synchronizing frequency information FM on the basis of axle rotational-frequency information FR and the wheel-diameter correction information WD.