Abstract: A damage detecting apparatus comprises a magnetic-flux generating unit, a first magnetic-flux detecting element, a second magnetic-flux detecting element and a supporting unit. The magnetic-flux generating unit generates a magnetic flux in an object to be inspected. The first magnetic-flux detecting element is detects a magnetic flux leaking from a circumferential part of the object. The second magnetic-flux detecting element is arranged, opposing the first magnetic-flux detecting element across the object and detects a magnetic flux leaking from any other circumferential part of the object. The supporting unit supports the first and second magnetic-flux detecting elements, enabling the first and second magnetic-flux detecting elements to change in position relative to each other in a diameter direction of the object.