A resin composition includes: a resin as Component (A); and an inorganic filler as Component (B). The Component (B) includes anhydrous magnesium carbonate as Component (b1) and aluminum oxide as Component (b2). Content of the Component (b1) falls within a range from 35% by volume to 65% by volume relative to 100% by volume of the Components (b1) and (b2) combined. Content of the Component (B) falls within a range from 60% by volume to 75% by volume relative to 100% by volume of the resin composition.