An automobile roller-type power generating device installed at the bottom of a vehicle body includes: a roller pivotally coupled to a camshaft and having a notch; a push slider having an arc bottom and installed in the notch of the roller, and the notch being in a shape corresponsive to the push slider and slightly greater than the push slider to allow the push slider to slide up and down; and a power generating mechanism installed above the pushrod. When the motor vehicle moves to roll the roller, the arc bottom presses the ground and slides into the roller to allow the push slider to slide up and down to transmit kinetic energy to the power generating mechanism, and the power generating mechanism converts the kinetic energy into electric energy to achieve the effect of generating power generation and storing electric energy into the battery.