An adaptive quantization technique is presented for HDTV image sequence coding to regulate the output channel buffer. The proposed technique controls quantization parameters, which are used for the quantization of the transformed coefficients, based on the local characteristics of the image, characteristics of the Human Visual System(HVS), and buffer status. By considering the local characteristics of the HVS as well as the buffer status, the coding distortions are uniformly distributed across the image and the visibility of distortion is minimized. The simulation is performed by applying the proposed adaptive quantization scheme to the GI's DigiCipher system, and a significant improvement of the proposed scheme compared to the conventional scheme where the qunatization parameter depends only on the buffer fullness was achieved.