Provided is a boron nitride/resin composite circuit board which has high heat radiation properties and high reliability. The boron nitride/resin composite circuit board is characterized by comprising: a platy resin-impregnated sintered boron nitride object which has a plate thickness of 0.2-1.5 mm and comprises 30-85 vol% sintered boron nitride object in which boron nitride particles having an average major-axis length of 5-50 [mu]m have been three-dimensionally bonded and 70-15 vol% resin; and a metal circuit constituted of copper or aluminum and bonded to each of both main surfaces of the sintered object. The circuit board is further characterized in that the ratio of the coefficient of thermal linear expansion (CTE1) at 40-150 DEG C in the plane direction of the resin-impregnated sintered boron nitride object to the coefficient of thermal linear expansion (CTE2) at 40-150 DEG C of the metal circuit, CTE1/CTE2, is 0.5-2.0.