Abstract: Disclosed is a coolant control valve unit having a sealing structure, the control valve unit including: a rotary valve provided with a valve coolant passage formed from an inner surface to an outer surface of the rotary valve; a valve housing in which the rotary valve is rotatably provided; a fitting coupled to the valve housing, and having a fitting coolant passage; and a sealing unit provided between a front surface of the fitting and the outer surface of the rotary valve, wherein the sealing unit includes: a sealing ring being in contact with the outer surface of the rotary valve; and a rubber ring provided on the front surface of the fitting, and bringing the sealing ring into contact with the outer surface of the rotary valve, wherein the rubber ring has an X-shaped cross-section, with a front groove, a rear groove, an inner groove, and an outer groove.