PURPOSE: To prevent a strut from being a hindrance to an excavating work, by a method wherein panels are supported by means of a temporary strut which can slide along rails enagaging the panels, and the temporary strut is moved as the excavation proceeds.

CONSTITUTION: An initial stay 5 is first erected into earth. A panel 6 is then inserted into a panel-support channel in the stay 5. The panels 6, positioned facing and opposite to stay 6, are held by means of a temporary strut located between the panels 6. The temporary strut, consisting of a compressed material 2 and a shoe 3, is slidably inserted in a strut supporting channel 12 in a perpendicular rail 1 engaging the panel 6 by means of hooking part 16. With this, excavation is conducted between the panels 6, and it continues in a manner to hold adistance between the pannels 6 by gradually sliding the strut. Unlike a conventional strut positioned between the stays 5, the temporary strut is prevented from being a hindrance to an excavating work. When the panels 6 are sunk to a given depth, the stay 5 is pressed in a manner to bring the one open side end of the panel 6 into a state to engage the panel-supporting channel.