To automatically and continuously detect the position of a crack tip two-dimensionally by providing an insulator for maintaining the insulation between planar resistors between first and second planar resistors.

An insulator base 2 comprising an insulation material, and a first planar resistor 14a where a plurality of first resistance lines 13a-13e are arranged in parallel between a pair of first gauge lead line connection part being arranged while they oppose each other on the insulator base 2 are constituted. Also, a plurality of second resistance lines 13f-13j are arranged in parallel in a direction that orthogonally crosses the direction of the first resistance lines 13a-13e of the first planar resistor 14a between a pair of second gauge lead line connection parts being arranged while they oppose each other, thus constituting a second planar resistor 14b. An insulator 15 for maintaining insulation is provided between planar resistors is provided between the first and second planar resistors 14a and 14b. Therefore, when a two-dimensional crack gauge 10 is stuck to an area near a point where a crack is generated, only the resistance of a planar resistor where the resistance line is cut changes out of two planar resistors being provided in directions that orthogonally cross each other.