A semiconductor module comprising: two insulating substrates each of which is made of AlN and each of which has a first plane and a second plane facing mutually opposite directions; a first conductor layer formed on the first plane of each of the two insulating substrates; a second conductor layer formed on the second plane of each of the two insulating substrates; a semiconductor device bonded to each of the first conductor layers with a first solder layer interposed therebetween; a heat dissipation plate that is formed in a rectangular shape when viewed planarly and that is bonded to both the second conductor layers with a second solder layer interposed therebetween; wherein the heat dissipation plate having: a deformed portion that is positioned at an intermediate part in the length direction of the heat dissipation plate when viewed from a width direction of the heat dissipation plate and that is deformed so as to become convex in a direction in which the second plane is pointed; and two inverted deformed portions that are positioned on both sides of the deformed portion and that are deformed so as to become convex in a direction in which the first plane is pointed, characterized in that the two insulating substrates are arranged side by side through a space in a length direction of the heat dissipation plate, the heat dissipation plate is curved so as to be convex in the direction in which the second plane is pointed as a whole when viewed from a width direction of the heat dissipation plate, and the deformed portion is disposed in the space between the two insulating substrates when viewed planarly, and the two inverted deformed portions lie on the two insulating substrates when viewed planarly respectively. two insulating substrates each of which is made of AlN and each of which has a first plane and a second plane facing mutually opposite directions; a first conductor layer formed on the first plane of each of the two insulating substrates; a second conductor layer formed on the second plane of each of the two insulating substrates; a semiconductor device bonded to each of the first conductor layers with a first solder layer interposed therebetween; a heat dissipation plate that is formed in a rectangular shape when viewed planarly and that is bonded to both the second conductor layers with a second solder layer interposed therebetween; wherein the heat dissipation plate having: a deformed portion that is positioned at an intermediate part in the length direction of the heat dissipation plate when viewed from a width direction of the heat dissipation plate and that is deformed so as to become convex in a direction in which the second plane is pointed; and two inverted deformed portions that are positioned on both sides of the deformed portion and that are deformed so as to become convex in a direction in which the first plane is pointed, a deformed portion that is positioned at an intermediate part in the length direction of the heat dissipation plate when viewed from a width direction of the heat dissipation plate and that is deformed so as to become convex in a direction in which the second plane is pointed; and two inverted deformed portions that are positioned on both sides of the deformed portion and that are deformed so as to become convex in a direction in which the first plane is pointed, characterized in that the two insulating substrates are arranged side by side through a space in a length direction of the heat dissipation plate, the heat dissipation plate is curved so as to be convex in the direction in which the second plane is pointed as a whole when viewed from a width direction of the heat dissipation plate, and the deformed portion is disposed in the space between the two insulating substrates when viewed planarly, and the two inverted deformed portions lie on the two insulating substrates when viewed planarly respectively.