The depth-first sphere decoder (SD) and the K-best algorithm have been widely studied as near optimum detectors. Depth-first SD has a non-deterministic computational throughput and K-best requires a sorting unit whose complexity is significant when a large K is used together with high modulation constellations. In this letter, we propose a MIMO detector that employs the trellis structure instead of the conventional tree searching. This detector can keep the computational throughput constant and reduce the complexity because the sorting is not required. From the simulation and complexity analysis, we investigate the advantage and drawback of the proposed detector.