PURPOSE: To obtain good appearance of both hull flange parts and to prevent flow of adhesive agent by forming the upper hull peripheral flange part in its upper surface shape tilting downward toward the peripheral edge and setting both upper and lower hull peripheral connection surfaces horizontal with respect to a base line.

CONSTITUTION: An upper hull 3, constituting a deck part with a fiber reinforced plastic(FRP) material, and a lower hull 2, constituting a bottom part with an FRP material, of two pieces are integrally connected, forming a water vehicle. A flange part 3a, provided in the periphery of the upper hull 3, constitutes the upper surface shape so as to tilt downward toward the peripheral edge, and connection surfaces 2b, 3b of flange parts 2a, 3a, provided in the periphery of both the hulls 2, 3, are horizontally constituted with respect to a base line B. Both the hulls are integrally formed by applying an adhesive agent 4 interposing to the connection surface. The adhesive agent is horizontally applied preventing its flow in the peripheral edge while holding the gracefulness in appearance shape of the flange part in both the hulls.