A fluid pressure cylinder includes first through fourth stepped portions provided in a multi-stepped manner on a first spigot joint of a head cover, and first through fourth stepped portions provided similarly in a multi-stepped manner on a second spigot joint of a rod cover. A cylinder tube is installed selectively on any one pair of the first through fourth stepped portions. Consequently, by preparing a new cylinder tube that differs in diameter, along with a new piston, and then installing the cylinder tube selectively on any one pair of the first through fourth stepped portions, a fluid pressure cylinder having a different bore diameter is constructed.