PURPOSE: To efficiently make a calculation by linking the earth retaining calculation data and calculated result with the excavation face data, extracting the required data from the earth retaining data, substituting them for the excavation face data, and preparing the desired work data.

CONSTITUTION: When the number (c) indicating the aimed excavation data is inputted from an input section 1 via a controller 4, the corresponding excavation data (d) are outputted from an excavation data file 3. The data (d) contain the number (f) indicating a linked earth retaining data file, and the earth retaining data (e) specified by the number (f) are outputted from an earth retaining file 2 in response to the output of the data (d). When outputs of the data (d), (e) are received, the layout diagram of piles to be installed, a deployment diagram, and an excavation work estimation table are displayed on a display section 5. A design change and a large-scale excavation plan can be quickly coped with, and the procedures required for excavation execution can be automated.