We aim to carry out the SOLAR-C satellite mission that follows the 3rd Japanese space solar observatory HINODE for elucidating a link between solar magnetic fields and solar activity. It has been found from HINODE observations that there are unexpected ubiquitous activities of tiny jets and waves in the 104K temperature chromosphere, and a new small-scale heating event with dynamical motions at the base of the corona near the chromosphere. These are understood as phenomena that are strongly associated with the magnetic field on the Sun. Based on unprecedented high-resolution imaging and spectroscopic observations the SOLAR-C will resolve the fundamental scales of magnetic structures over the solar atmosphere from the photosphere to the corona that have been found from HINODE observations. It will reveal the origins of solar activity through the measurement of magnetic fields in the chromosphere.