A cooling water control apparatus (30) is a cooling water control apparatus for controlling a cooling apparatus having a first pipe (181) which circulates cooling water through an engine (20); a second pipe (182) which circulates the cooling water not through the engine; and a switching valve (13) whose state is changed between opened and closed states, and has: a detecting device (30) which detects first temperature (thw) of the cooling water in a pipe portion (181b, 181c) of the first pipe between the engine and the switching valve; and a determining device (30) which determines that there is failure of the switching valve whose state is the closed state, if required period from the output of the command for changing the state of the switching valve from the opened state to the closed state until the first temperature reaches predetermined temperature is larger than predetermined target period.