A pipe joint and a joint connection device have simpler configurations while preventing fluid leakage and absorbing misalignment of shaft centers. A pipe joint includes a male joint and a female joint into which the male joint is inserted. The male joint has a male joint main body and a cap that is fixed at a base end of the male joint main body, with a male joint O-ring interposed between the cap and the male joint main body. The cross-section diameter of the male joint O-ring is 3 to 10 mm, and a clearance-between the male joint main body and the cap is 3 to 13% of the cross-section diameter of the male joint O-ring.