To provide a sensor, a microphone, a blood pressure sensor, and a touch panel with which it is possible to improve sensitivity.SOLUTION: According to one embodiment, a sensor includes a deformable film part and a first detection element provided in the film part. The first detection element includes a first magnetic layer, a second magnetic layer, and a non-magnetic first intermediate layer provided between the first and the second magnetic layers. The first magnetic layer includes a first film containing Fe and Co, a second film containing Fe and Co, a third film, and a fourth film. The third film is provided between the first and the second films, and contains at least one selected from the group consisting of Cu, Au, Ru, Ag, Pt, Pd, Ir, Rh, Re and Os. The fourth film is provided between the third and the second films, and contains at least one selected from the group consisting of Mg, Ca, Sc, Ti, Sr, Y, Zr, Nb, Mo, Ba, La, Hf, Ta, and W.SELECTED DRAWING: Figure 1【課題】感度を向上できるセンサ、マイクロフォン、血圧センサ及びタッチパネルを提供する。【解決手段】実施形態によれば、センサは、変形可能な膜部と、膜部に設けられた第１検知素子と、を含む。第１検知素子は、第１磁性層と、第２磁性層と、第１磁性層と第２磁性層との間に設けられ非磁性の第１中間層と、を含む。第１磁性層は、Ｆｅ及びＣｏを含む第１膜と、Ｆｅ及びＣｏを含む第２膜と、第３膜と、第４膜と、を含む。第３膜は、第１膜と第２膜との間に設けられ、Ｃｕ、Ａｕ、Ｒｕ、Ａｇ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｈ、Ｒｅ及びＯｓよりなる群から選択された少なくとも１つを含む。第４膜は、第３膜と第２膜との間に設けられ、Ｍｇ、Ｃａ、Ｓｃ、Ｔｉ、Ｓｒ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｂａ、Ｌａ、Ｈｆ、Ｔａ及びＷよりなる群から選択された少なくとも１つを含む。【選択図】図１
