Neutrinos are generated via various physics processes in the Sun, such as nuclear fusion in the core, and solar flares due to the reconnection of magnetic field lines above sun spots. Those neutrinos provide information about neutrino properties, nuclear physics, and astrophysics. Super-Kamiokande (SK) is a multi-purpose water Cherenkov detector in Japan and studies neutrino interactions in the energy range from MeV to GeV. In this presentation, we overview the results of neutrinos from the Sun in the SK detector; the measurement of the neutrino energy spectrum and the oscillation parameters of solar neutrinos, and the search for neutrinos from powerful solar flares. In addition, we discuss future prospect of these studies after loading gadolinium (SK-Gd).