To solve a problem wherein bows of leeward side hulls lower in a catamaran hydrofoil yacht for connecting the left and right hulls by a connecting shaft so as to be relatively rotatable.

Rear parts of a pair of left and right hulls 10A and 10B for connecting a longitudinal directional intermediate part to both end parts of the connecting shaft 12 extending in the lateral direction so as to be only rotatable are rotatably connected by a connecting beam 13. The longitudinal directional intermediate part and front parts of the respective hulls are provided with rear struts 30 and front struts 40 for respectively arranging a rear hydrofoil 31 and a front hydrofoil 41 in a lower end part. A mast 60 is arranged on the connecting shaft, and the front struts are steered by a steering device 50. A crew support part 21 of a deck 20 for supporting crews is made rigid for not contacting with the respective hulls, and is supported by a first support member 22 for connecting a front edge part to the connecting shaft so as not to laterally incline, and a second support member 23 for connecting a rear edge part of the crew support part to the connecting means so as not to hinder a lateral inclination.