subject has a large number of preferably much small grooves 111 c u2033 extended along the oblique direction to a traverse direction x direction in the substrate 111 u2033 the other configurations according to the present alternative are almost the same as those according to the embodiment in fig1 because the measurement surface 111 a u2033 on the substrate has a large number of machined grooves 111 c u2033 extended along the oblique direction the sticktion hardly occurs accordingly a damage probability by the sticktion is drastically reduced and therefore the durability and lifetime can be improved in a large extent fig1 shows a perspective view schematically illustrating a configuration of the ect probe according to a still further embodiment of the present invention and fig1 shows a cross sectional view taken along with line xvi u2014 xvi in fig1 here fig1 shows a view from the side of the opposite surface to that of fig2 that is of the measurement surface facing to the subject in these figures reference numeral 151 indicates a flexible substrate formed of an insulative material such as polyimide 152 indicates a meander type exciting coil including coil conductors formed as the planar pattern turned back on the opposite surface 151 b to the measurement surface 151 a of the substrate.