A method to improve positioning accuracy of an indoor messaging system (IMES) was developed. This method uses Doppler shifts (produced by moving a receiver antenna) and three-dimensional attitude to determine the position of the receiver. A rotation-type Doppler-measurement system applying this method was developed. To evaluate the system, two experiments were conducted: in one, rotation radius of a movable receiver antenna was varied; in the other, position where positioning is conducted was varied. The experimental results show that the method can achieve centimeter- to decimeter-level positioning accuracy.