According to one embodiment, a sensor includes a support body, a film portion, a first sensing element, and a structure body. The first sensing element is fixed to the film portion, and includes a first magnetic layer, a first opposing magnetic layer, and a first intermediate layer. The structure body includes a first region overlapping the support body, and a second region being continuous with the first region and overlapping the film portion. The structure body includes a first structure body layer, a first opposing structure body layer, and a first structure body intermediate layer. The first opposing structure body layer is provided between the first structure body layer and the support body and between the first structure body layer and the film portion. The first structure body intermediate layer is provided between the first structure body layer and the first opposing structure body layer.