To provide a composition for a three-dimensional integrated circuit capable of forming a filling interlayer excellent in thermal conductivity also in a thickness direction, using agglomerated boron nitride particles excellent in the isotropy of thermal conductivity, disintegration resistance and kneading property with a resin. A composition for a three-dimensional integrated circuit, comprising agglomerated boron nitride particles which have a specific surface area of at least 10 m2/g, the surface of which is constituted by boron nitride primary particles having an average particle size of at least 0.05 μm and at most 1 μm, and which are spherical, and a resin (A) having a melt viscosity at 120° C. of at most 100 Pa·s.