Abstract: In the method for detecting liquid leak of the present invention, the inventive cable, i.e., a parallel pair or a coaxial cable insulated with porous polymer material, is placed along or under a storage and/or transport means for conveying chemicals. If leakage occurs, the leaked liquid permeates into fine pores in the porous insulation material separating two conductors from each other, and varies the characteristic impedance of the cable to some detectable extent. The variation of impedance is electrically measured by a pulse reflection method (TDR). The inventive method comprises; sending pulse waves from one end of the cable, sensing the reflected and deformed pulse shape, and thus detecting and locating the liquid leak.