A resin composition including an epoxy resin monomer, a novolac resin including a compound having a structural unit represented by Formula (I), and a filler; in which the filler has at least 4 peaks in a particle size distribution measured by laser diffractometry, in which four of the peaks are present respectively in ranges of not less than 0.01 μm and less than 1 μm, not less than 1 μm and less than 10 μm, from 10 μm to 50 μm, and from 20 μm to 100 μm, and in which a peak present in a range of from 10 μm to 50 μm includes an aluminum oxide particle, and a peak present in a range of from 20 μm to 100 μm includes a boron nitride particle. In Formula (I) each of R1, R2 and R3 independently represents a hydrogen atom, an alkyl group, or the like. m represents 0 to 2, and n represents 1 to 7.