We propose an electron-tracking Compton telescope with a gaseous Time Projection Chamber (TPC) and a position-sensitive scintillation camera. In this detector, both the energy and direction of the Compton recoil electron are precisely measured by the gaseous TPC, while those of the Compton scattered gamma ray are also measured by the scintillation camera. This detector realizes a full tracing of the Compton scattering process, including the scattered direction of the low energy recoil electron. Measuring the direction of the recoil electron by micro pattern-TPC, the incident gamma ray is determined only on a small segment of the Compton event circle. The fine tracking of recoil electron realizes the high background rejection efficiency by kinematics, which is a great advantage under the high background environment or crowded source region. For demonstrating this concept, a prototype telescope has been developed.