A coolant pump for a vehicle may include an impeller mounted at one side of a shaft and pumping a coolant, a pulley mounted at the other side of the shaft and receiving a torque, a pump housing of which an outlet for the coolant to flow out therethrough is formed thereto, an inflow portion including a first inlet and a second inlet configured for receiving coolant, a slider of which a first closing portion selectively closing or opening the outlet and a second closing portion selectively closing or opening the second inlet are formed thereto, and the slider disposed slidable along longitudinal direction of the shaft and a driver moving the slider.