A band holder holds a clamp band for a hose. The band holder includes an arm for covering an outer peripheral portion of the hose, connecting portions provided at free ends of the arm for connecting the free ends to form a circular shape of the arm, and a holding portion projecting from the arm for holding the clamp band. A fixing device fixes at least the holding portion to the hose. A hose assembly includes the band holder, a flexible hose to be connected to a tubular member, and a clamp band covering an outer surface of the hose for connecting the hose to the tubular member. The clamp band includes a band portion, and a screw unit provided at ends of the band portion for a clamp operation so that the screw unit tightens the band portion.