Free-viewpoint image synthesis (FVIS) refers to the process of generating novel viewpoint images from a set of multi-view images. Most of the conventional FVIS methods were based on image blending, so that they are subject to a fundamental limitation in resolution: the output resolution is lower than or at most equal to that of the input images. A reasonable approach to overcome this limitation is to replace image blending with reconstruction-based super-resolution. Following this idea, we propose a new FVIS method named as super-resolution plane sweeping by extending general plane sweeping methods. We also propose an adaptive weighting scheme to make super-resolution reconstruction operate only on the pixels where it improve the quality. Experimental results with real images are presented to show the effectiveness of our method.