Recently, various objects have become targets for sensing in order to realize an IoT society, and sensors are required higher sensitivity and miniaturization. In application of many automotive, aerospace, and industrial fields, there is a high need for compact sensors to measure mechanical quantities such as strain, stress. Strain gauge are intended to measure the magnitude and direction of the strain and the magnetostrictive effect in ferromagnetic films can be applied to strain detection. In this research, a GIG (Granular in Gap) structure [1] is used for a new strain gauge. It has a structure in which a granular film is sandwiched between soft magnetic yokes. When the strain is applied to the device, the change of strain is detected as a resistance change in the granular film. Co-AlO and amorphous(a)-FeSiBNb were employed as the granular film and the soft magnetic yoke of the strain gauge. The thickness of Co-AlO film and a-FeSiBNb yoke was 300 nm. The structure of the strain gauge is indicated in the inset of Figure 1. The gap length was estimated to be approximately 4 µm. An AC voltage at 80Hz supplied from a lock-in-amplifier (LIA) is applied to the series circuit of the gauge and a variable resistor. When the strain is applied to the gauge, the strain is detected as a voltage of the gauge by LIA. The MR ratio of the Co-AlO granular film before processing into a GIG element was about 6%. The magnetostriction constant of a-FeSiBNb yoke was 30.4ppm. A magnetic field of 5 Oe must be applied in direction of H⊥gap in order to align the magnetic moments of yokes. The granular film becomes a low resistance state due to a magnetic field appeared in the gap yielded by magnetic poles at the edge of yokes. When the strain is applied in direction of H//gap, the magnetic moments of yokes change its direction, increasing the resistance of granular film owing to the decrease of the magnetic field in the gap. The dependence of output voltage on the applied strain ε is shown in Fig.1. The blue circles are the result of increasing strain, and the red circles are the result of decreasing strain. The output voltage became large with increasing strain, and gradually almost constant because the magnetic moments of yokes saturated in direction of H//gap. This indicates that the strain up to about 6.0 × 10^-5 can be detected. The gauge factor estimated was approximately 50, larger than that of a typical metal strain gauge. Reference [1] N. Kobayashi et al., J. Magn. Magn. Mater. 188. 30 (1998).