Provided is an insulated circuit board including a ceramic substrate, a circuit layer that has a circuit pattern formed thereon and is bonded to one surface of the ceramic substrate, and a metal layer that is bonded to the other surface of the ceramic substrate, the ceramic substrate has a three-point bending strength, which is based on JIS 1601 2008, of 600 MPa or more, the circuit layer and the metal layer are made of copper or a copper alloy, the circuit layer is formed of a plurality of punched sheets bonded to the ceramic substrate at an interval, the thickness of the circuit layer is 0.4 mm or more and 2.0 mm or less, when the bonding area of the circuit layer is represented by S1, and the bonding area of the metal layer is represented by S2, the area ratio S1/S2 is 0.5 or more and 0.8 or less, and, when the thickness of the circuit layer is represented by T1, and the thickness of the metal layer is represented by T2, the thickness ratio T1/T2 is 1.2 or more and 1.7 or less.
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