According to one embodiment, a sensor includes a film portion, one or more detectors fixed to the film portion, and a processor. The detector includes first and second detecting elements. The first detecting element includes a first magnetic layer. The second detecting element includes a second magnetic layer. A first change rate of a first signal is higher than a second change rate of the first signal. The first signal corresponds to a first electrical resistance of the first detecting element. A change rate of a second signal with respect to the change of the magnitude of the strain is higher than the second change rate. The second signal corresponds to a second electrical resistance of the second detecting element. The processor is configured to perform at least a first operation of outputting a second value. The second value is based on the second signal and a first value.