PURPOSE: To eliminate the flapping a hose generated in association with gun shaking motion in the robotization of gun spray work of mortar or the like in building and civil engineering work by providing a joint with a male part, a female part and a cover respectively having spherical parts.

CONSTITUTION: A male part 2 with the spherical inner surface slidably engaged with the spherical outer surface of a female part 1 is fitted into the female part 1 with the spherical outer surface, and the fit-in state of the female part 1 and male part 2 are held by a cover 3 having the same spherical inner surface as the male part 1 and adjusted to the end part of the male part 1. The spherical surface of the male part 2, female part 1 and cover 3 is provided with appropriate clearances, and the leakage of a fluid is prevented by an O-ring 5 fitted into an O-ring groove 4. Constantly moving parts are provided with a grease nipple 6 and a grease sump 7 so as to guarantee smooth movement.