<p>It is possible to detect a coolant leak including identification of a position in a coolant circuit of a coolant device from which a coolant leaks. A coolant leak detection method detects a coolant leak from a coolant circuit (10). A fluid holding body (88) for holding a fluid caused by a coolant or a coolant leak is arranged at a portion of the coolant circuit (10) for detecting the coolant leak or in the vicinity of the portion. An impedance of the portion including the fluid holding body (88) is measured by an impedance measuring device (9).</p>
