A position calculating system for a haulage vehicle including wheels and a body frame mounted on the wheels. The system includes an attitude detection sensor fixed on the body frame, a wheel rotational speed sensor, a loading status information acquiring unit, a correction amount setting unit, a velocity vector calculating unit, and a position calculating unit. The loading status information acquiring unit acquires loading status information indicating whether the body frame is in a loaded state or in an unloaded state. The correction amount setting unit calculates, based on the attitude information, a correction amount required for bringing detection axes in the loaded state into coincidence with corresponding detection axes in the unloaded state. The velocity vector calculating unit calculates the velocity vector of the haulage vehicle. The position calculating unit calculates a position of the haulage vehicle by using the velocity vector.
