This part of IEC 63203-401-1 specifies a method of evaluating a stretchable resistive strain sensor for wearable electronic devices. Stretchable strain sensors are key components for wearable applications used for e-skin, e-textile, soft robot, human motion detection such as smart glove, and sports performance monitoring. Stretchable strain sensors can be attached to clothing or the human body and differ from conventional metal-foil strain gauges in terms of strain amount, stretchability, and application. Depending on the material used, there are several types of stretchable strain sensors, including resistive, capacitive, and piezoelectric. This standard specifies only resistive-type or resistance change type stretchable strain sensors, which consist of any resistive-material film deposited onto or bonded to a nonconductive stretchable substrate. The stretchable resistive strain sensor can also be produced with other technologies than the film deposit methods. Standardization of elongation and force measurement will be a next target of this standard. The objective of this document is to define the standard test methods to evaluate the performance and reliability of the stretchable strain sensor. This standard test method is not intended to evaluate the physical properties of the sensor s material such as the elastic modulus, elastic limit, and Poisson s ratio.