This paper investigates power gating implementations that mitigate power supply noise. We focus on the body connection of power-gated circuits, and examine the amount of power supply noise induced by power-on rush current and the contribution of a power-gated circuit as a decoupling capacitance during the sleep mode. To figure out the best implementation, we designed and fabricated a test chip in 65nm process. Experimental results with measurement and simulation reveal that the power-gated circuit with body-tied structure in triple-well is the best implementation from the following three points; power supply noise due to rush current, the contribution of decoupling capacitance during the sleep mode and the leakage reduction thanks to power gating.