PROBLEM TO BE SOLVED: To provide a crack-monitoring material and a crack monitoring system, for economizing the inspection cost, enhancing inspection reliability, facilitating site work execution, and maintaining the detection function over a long period of time.
SOLUTION: When a crack C1 occurs in a steel structure 1, the crack-monitoring material 3 applied to and formed on a surface of the steel structure 1 is partly broken to cause a crack C1 to occur. The electrical resistance of conductive layers 4a in respective monitored areas A1 to A49 is measured by an energized-state measurement part 7. The change in the electrical resistance is evaluated by an evaluation part 9 to specify the monitored area A1. When the crack C1 occurs in the monitored area A1, the amount of change of resistance value between electrodes is increased, in a direction crossing the progressing direction of the crack C1, in comparison with a change in resistance value between electrodes in the same direction as the developing direction of the crack C1. Because of this, the progressing direction of the crack C1 is specified, when measuring electric resistance between electrodes confronting longitudinally, laterally, and obliquely, in the monitored region A1 of the conductive layers 41 by the measurement part 7 to evaluate a change in electric resistance by the evaluation part 9.