It is well known that M-ary spread spectrum (M-ary/SS) system is superior to direct-sequence spread spectrum (DS/SS) system under additive white Gaussian noise (AWGN), and can achieve high spectral efficiency. In this paper, we propose use of M-ary/SS for the purpose of improving the anti-noise performance in synchronized chaotic communication system. However, in the M-ary/SS system, since the transmitted sequences change with each frame, synchronization is difficult. In this system, frame synchronization performance is improved by using chaotic synchronization. The validity of the proposed system is shown by computer simulations