The present invention relates to a coolant control valve apparatus which comprises a failsafe valve opened immediately when the temperature of an engine coolant rises due to a valve malfunctioning. An engine cooling system of the present invention comprises a main passage (4) which circulates a coolant between an engine (1) and a radiator (3), and a bypass passage (5) bypassing the radiator (3). A coolant control valve apparatus (10) of the present invention comprises a main valve (11) which adjusts a flow rate of the coolant at the main passage (4) to control the flow rate of the coolant at the main passage (4), and further comprises a bypassing passage (67) disposed to diverge from the main passage (4) and bypass the main valve (11). The present invention further comprises a valve main body (41) which opens and closes the bypassing passage (67), and a temperature detection medium (42) which allows the valve main body (41) to be opened and closed according to the temperature of the coolant. The temperature detection medium (42) is disposed at a portion where the bypassing passage (67) and the bypass passage (5) diverge from each other.
