A collapsible boat including:
   a boat bottom, the boat bottom being fabricated by curving a thin, flat plate into a quadric surface such that a predetermined keel line, a predetermined chine line, and a predetermined stern line are included on or above the flat plate; dividing a portion of the flat plate, which portion is surrounded by the keel line, the chine line and the stern line, by a plurality of straight lines; and connecting a plurality of flat plate pieces together such that the flat plate pieces are bendable, the flat plate pieces being formed in configurations which respectively match divided shapes; and
   a buoyancy body, the boat bottom being installed at a bottom portion of the buoyancy body so as to be attachable to and removable from the buoyancy body.
The collapsible boat has a curved configuration, sufficient strength, superior ability to ride over waves, and excellent seaworthiness.