A narrow channel width between a circuit under test and a tester increases the testing time. In this paper, we propose a channel width compression method when the channel width is limited. A given test sequence is partitioned into sub-sequences, whose widths can be compressed under the limited width. Each sub-sequence is compressed and expanded by a proposed dynamically re-configurable circuit located between the circuit under test and the tester. Since the hardware overhead depends on the number of partitions for a test sequence, a procedure to partition a given test sequence into a minimum number of sub-sequences under the channel width limitation is proposed. Experimental results show that our method can compress the width of a test sequence into a half through a quarter with a relatively small number of partitions.