An RRAM structure includes a substrate. An RRAM is embedded in the substrate. The RRAM includes a bottom electrode, a metal oxide layer and a top electrode. A first doped region is embedded in the substrate and surrounds the bottom electrode. A transistor is disposed on the substrate and at one side of the RRAM. The transistor includes a gate structure on the substrate. A source is disposed in the substrate and at one side of the gate structure. A drain is disposed in the substrate and at another side of the gate structure. The first doped region contacts the drain.