A strain measurement device and a strain measurement method

A strain measurement method comprising:

• a step of preparing a strain measurement device including a substrate, a first element formed on the substrate and having a first magnetization layer, a second magnetization layer whose change in a magnetization direction when strain is applied to the substrate is larger than that of the first magnetization layer, and a first spacer layer placed between the first magnetization layer and the second magnetization layer, and a second element formed on the substrate and having a third magnetization layer, a fourth magnetization layer whose change in a magnetization direction when strain is applied to the substrate is larger than that of the third magnetization layer, and a second spacer layer placed between the third magnetization layer and the fourth magnetization layer, wherein, in a state where no strain is applied to the substrate, at least one magnetization direction out of the magnetization direction of the first magnetization layer, the magnetization direction of the second magnetization layer, the magnetization direction of the third magnetization layer, and the magnetization direction of the fourth magnetization layer is different from the other magnetization directions;
• a step of applying strain to the substrate;
• a step of applying a current to the first element and the second element;
• a step of measuring electrical resistance at the first element and the second element;
• and
• a step of subtracting or dividing one of the electrical resistance at the first element and the electrical resistance at the second element from or by the other of the electrical resistance at the first element and the electrical resistance at the second element.