A floating body includes a main body having first and second surfaces opposite to each other and a first side surface connecting the first and second surfaces and first and second joining parts located on the first side surface to be opposite to each other in a first direction parallel to a ridge line defined by the first surface and the first side surface. The first and second joining parts each include a first portion located on the first side surface and a second portion connected to the first portion to face the first side surface. End portions of the first and second joining parts face each other. A minimum distance between the end portions is greater than twice a width of the second portion in the first direction, and is smaller than a minimum distance between the first portions of the first and second joining parts.