Abstract: A method for monitoring flow condition of a liquid metal which employs a detector consisting of an excitation coil applied with an a.c. current and at least two detection coils disposed on both sides of said excitation coil. The detector is disposed in the flowing direction of the liquid metal and a peak point of the cross-correlation function of fluctuation signals occurring in said detection coils is examined. By detecting the moving direction, the polarity and the magnitude of the peak point, the flow condition can be comprehensively ascertained, such as a change in flow velocity, a change in void fraction, the presence of voids and transit velocity of void.