To provide an epoxy resin composition, which gives a cured product with excellent tracking resistance, has good fluidity, and gives a cured product with excellent humidity resistance, for sealing a semiconductor.

The epoxy resin composition for sealing a semiconductor includes: (A) an epoxy resin; (B) a curing agent; (C) spherical cristobalite with average particle diameter of 0.3-50 μm and sphericity of ≥0.7; and (D) an inorganic filler other than the component (C). The content of the component (C) is 10-50 mass% of the total of the component (C) and the component (D), and the component (C) includes no metal hydroxide.