We propose to use an extremely unbalanced interferometer (EUI) as a wavefront correcting input to a stellar coronagraph for direct exoplanet observation. Since wavefront error causes incomplete suppression of stellar light, an EUI aims to precisely correct the wavefront incident on the coronagraph to a level better than in the visible wavelength range. Compared to the previous unbalanced interferometer, which incorporated a nulling function, the proposed EUI does not introduce the nulling function. EUI does not use a precise deformable mirror. It increases the accuracy of a wavefront control effectively because of the coherent summation with an amplitude imbalance. It enables obtaining the desirable coronagraphic contrast for Earth-like exoplanet imaging.