A piping sensor which is interposed within an existing pipeline for a predetermined fluid provided in either a structure or the ground and detects abnormalities of the piping and the surrounding of the piping, the piping sensor comprising: a pair of connection flanges which is flange-connected to an upstream side and a downstream side, respectively, of a section part dividing the pipeline in the midst of the same, an inner pipe which connects the section part of the pipeline between the connection flanges in a manner of allowing fluid circulation, a bypass pipe having a flow path branching in a bypassing manner from a position of the inner pipe closer to the upstream side towards a spaced-away outer periphery of the inner pipe, and merging again in a position of the inner pipe closer to the downstream side, a rotor provided within the flow path of the bypass pipe and freely rotatably about the inner pipe and itself rotates about the pipe axis of the inner pipe by the fluid circulation to the flow path of the bypass pipe, an electromotive device which is closely fixed on at least either the inner circumferential surface or outer circumferential surface of the rotor or a face constituting the inside of the structure, and generates electricity by the rotation of the rotor, and a detector which is disposed in a passage of the flange structure by the pair of connection flanges or in a passage between the pair of connection flanges, and is capable of detecting a detection signal in correlation with the fluid circulation within the pipeline P further upstream and/or downstream of the section part, and in which self-power generation is performed by the electromotive device, and the situation of the sectioned and connected pipeline or the surroundings of the pipeline is detected by an electromotive state by the electromotive device and a detection signal. a pair of connection flanges which is flange-connected to an upstream side and a downstream side, respectively, of a section part dividing the pipeline in the midst of the same, an inner pipe which connects the section part of the pipeline between the connection flanges in a manner of allowing fluid circulation, a bypass pipe having a flow path branching in a bypassing manner from a position of the inner pipe closer to the upstream side towards a spaced-away outer periphery of the inner pipe, and merging again in a position of the inner pipe closer to the downstream side, a rotor provided within the flow path of the bypass pipe and freely rotatably about the inner pipe and itself rotates about the pipe axis of the inner pipe by the fluid circulation to the flow path of the bypass pipe, an electromotive device which is closely fixed on at least either the inner circumferential surface or outer circumferential surface of the rotor or a face constituting the inside of the structure, and generates electricity by the rotation of the rotor, and a detector which is disposed in a passage of the flange structure by the pair of connection flanges or in a passage between the pair of connection flanges, and is capable of detecting a detection signal in correlation with the fluid circulation within the pipeline P further upstream and/or downstream of the section part, and in which self-power generation is performed by the electromotive device, and the situation of the sectioned and connected pipeline or the surroundings of the pipeline is detected by an electromotive state by the electromotive device and a detection signal.