Provided is a stretching mat whereby high stretching effects are obtained relative to the conventional configuration. An air bag is provided to a stretching part for curving and protruding in a ridge shape along a front-rear direction, and transformation is possible between a gently curved state in which the air bag is deflated and a strongly curved state in which the air bag is swollen and more strongly curved than in the gently curved state. A configuration is also adopted in which air is supplied to the air bag in a state in which a portion of a body is resting on the stretching part, and the stretching part transforms from the gently curved state to the strongly curved state over time, after which the supply of air is stopped and the strongly curved state of the stretching part is maintained.
