To provide an assembly of a fitting and a dust cover capable of preventing a problem on intrusion of a construction material of the dust cover into a clearance of a joining portion of the fitting when the dust cover is blow-molded to the fitting formed by joining an upper fitting and a lower fitting, and integrally assembled with the fitting.

In this assembly 87 of the fitting 16 formed by joining the cup-shaped upper fitting 36 in which a lower portion of cushion rubber is elastically fitted and retained, the inverted cup-shaped lower fitting 38 for retaining an upper portion of a bound stopper 47 in a fitted state, for mounting and fixing the piston rod, and the dust cover 86 as blow-moldings, at least a part positioned at an outer peripheral side of a joining portion of a lower bottom portion 40 and an upper bottom portion 44, of the fitted assembled portion 88 of the dust cover 86, is a thick portion 96 partially thicker than the other part.