According to one embodiment, a pressure sensor includes a base and a sensor unit provided on the base. The sensor unit includes a transducing thin film having a first surface, a first strain sensing element provided on the first surface, and a second strain sensing element provided on the first surface. The first strain sensing element includes a first magnetic layer, a first film having a first oxygen concentration, a second magnetic layer provided between the first magnetic layer and the first film, and a first intermediate layer provided between the first and the second magnetic layer. The second strain sensing element includes a third magnetic layer, a second film having a second oxygen concentration different from the first concentration, a fourth magnetic layer provided between the third magnetic layer and the second film, and a second intermediate layer provided between the third and the fourth magnetic layer.