We have developed a strain gauge sensor to measure two axial dynamic strain and temperature evolution during ultrasonic flip-chip bonding. The sensor detects strain from change in resistance due to the piezoresistance effect of Si and temperature from change in current-voltage characteristics of pn-junction. The spatial resolution of the sensor is 20 μm. Au planar microbumps were used for the measurement. The number of bumps in the test chip was 12100. The measurement results of dynamic strain indicated the generation of a large strain at the initial stage of ultrasonic vibration. On the other hand, rise in temperature up to only a few degrees was observed during the ultrasonic vibration. Therefore, the damage is considered to be generated by mechanical strain at the initial stage of ultrasonic vibration. The sensing method and results will contribute to improving the reliability of three dimensionally integrated electronic devices.