PURPOSE: To obtain a strong horizontal bearing force by strongly driving an object such as large (or huge) steel pipes, etc., into the seabed by providing a pressure air supply and discharge type supporting cylinder to vertically move a striker and having its lower end under water to a framework sliding on a catamaran type barge.

CONSTITUTION: A striker 3 is supported in a vertically slidable manner on a framework 2 horizontally moving in the longitudinal direction of catamaran type barge 1. Hull-coupling shafts 10 are provided in a vertically movable manner to the four corners of the hull 1, and the hull 1 is fixed to the seabed 5. The striker 3 is provided with two supporters 20 vertically movable in relation to the framework 2, a floating cylinder 24 with an air chamber 22 positioned in water at the lower end of the supporters 20, and a mechanism to supply air to and also discharge air from the air chamber 22. The supporters 20 are vertically moved by supplying pressure air to or discharging pressure air from the floating cylinder 24 to drive an object to be penetrated. The object can be continuously driven by sliding the striker 3 on the hull without moving the hull 1. A strong striker capable of striking huge steel pipe, etc., can be obtained.