The present invention provides a system for supporting construction of an underground continuous wall wherein a control server connected to each excavator through a network comprises a ground strength evaluating unit for obtaining the ground strength distribution of the ground to be excavated in a depth direction on the basis of imparted ground property; a necessary excavating ability operating unit for obtaining the accumulated ground strength from said ground strength distribution, and obtaining necessary excavating ability of said cutter post balanced with the excavation resistant force obtained from said accumulated ground strength; a comparing unit for comparing the obtained said necessary excavating ability with the excavating ability of the excavator carried into a work site; an excavating efficiency evaluating unit for evaluating excavating efficiency on the basis of the comparison result of the comparing unit; and a transmit-receive unit for receiving a request from said excavator and transmitting the evaluation result of excavating efficiency by the excavating efficiency evaluating unit to the excavator, whereby enabling to provide necessary information corresponding to the condition of the ground and to carry out efficient construction work of a continuous wall.