The complexity of geotechnical engineering and variability in construction circumstances of large extra caissons make the problem of maintaining appropriate sink attitude quite difficult, especially in keeping sink uniformity and achieving the expected final sink depth. A new construction control method is presented using H_∞ theory, considering uncertainties in the mechanics model and external noise in the construction site parameters. The design method of an H_∞ controller has consequently been obtained for large extra caissons. Control results using only constructor experiences are compared with simulation results using the H_∞ controller for a practical engineering situation, which indicates that the H_∞ controller is successful in maintaining sink uniformity, avoiding sink as well as in achieving the expected final sink depth.