A method for fabricating a capacitor is provided. The method for fabricating a capacitor includes forming a dielectric layer over a lower electrode on a substrate, forming an upper electrode over the dielectric layer, forming a hard mask over the upper electrode, etching the hard mask to form a hard mask pattern, etching the upper electrode to make the dielectric layer remain on the lower electrode in a predetermined thickness, forming an isolation layer along an upper surface of the remaining dielectric layer and the hard mask pattern, leaving the isolation layer having a shape of a spacer on one sidewall of the hard mask pattern, the upper electrode, and the dielectric layer, and etching the lower electrode to be isolated.