A small boat with a sponson for preventing splashing of spray onto the deck of the boat. The small boat is provided with a hull sponson at an outer periphery of the hull in order to fit the deck constituting an upper part of a boat body to the hull constituting a lower part of the boat body. A deck sponson is provided at an outer periphery of the deck, and the deck sponson is overlaid so as to bond with the hull sponson. The extent of projection of one member of the hull sponson and the deck sponson at the front section of the boat body is larger than the extent of projection of a member of the hull sponson and the deck sponson at a second member of the boat body. As a result, when the small boat is gliding and collides with a wave, the sponson prevents spray from the wave from splashing onto the deck.