To provide a work execution controlling method for an existing cutoff plate allowing objectively judging whether the execution of the existing cutoff plate is normal or not by a simple method in a method for constructing an underground cutoff wall by penetrating a succeeding cutoff plate into the existing cutoff plate penetrated in an underground vertical direction, engaging the succeeding cutoff plate to the existing cutoff plate.

In the method for constructing the underground cutoff plate by providing each one of a male engagement part and a female engagement part on both side parts of a vertical direction of the cutoff plate and penetrating a succeeding cutoff plate into the existing cutoff plate penetrated in the underground vertical direction, engaging the male engagement part and the female engagement part adjacent each other, this method is the execution controlling method for the existing cutoff plate for judging whether the execution of the existing cutoff plate is normal or not by installing a load cell for measuring load applied in a lower direction of the cutoff plate at a ground surface portion on an upper side of the existing cutoff plate and time-sequentially measuring the load, when the succeeding cutoff plate is engaged to the existing cutoff plate.