A circuit board assembly comprising: a circuit board having an area (A) on which electronic components are mounted, and being provided with a plurality of mounting holes and a through-hole , in a portion of the circuit board other than the area (A); and a cover that surrounds and supports the circuit board , the cover covering the circuit board with a clearance interposed between the cover and a portion of the circuit board , which includes the area, wherein the cover includes a first cover to cover a first surface of the circuit board and a second cover to cover a second surface of the circuit board , and the cover is provided, on its inner surface, with a suppression portion passing through the through-hole of the circuit board , projecting from at least one of the first cover and the second cover , and configured to suppress the inner surface from approaching the area when external pressure is applied to the cover , characterised in that the first cover is made of synthetic resin and has a circuit board attachment portion and a cable terminal cover portion integrally joined to a base end of the circuit board attachment portion , a plurality of board-resting portions which are arranged in a width direction on a surface of the circuit board attachment portion at a central portion thereof are each provided with a mounting projection , the circuit board is placed on the board-resting portions , and leading ends of the mounting projections pass through the mounting holes and are heated in a state where the leading ends project from the circuit board , and melted to cover the mounting holes and their peripheries, and the melted leading ends are then solidified to adhere to the surface of the circuit board , which faces the second cover . a circuit board having an area (A) on which electronic components are mounted, and being provided with a plurality of mounting holes and a through-hole , in a portion of the circuit board other than the area (A); and a cover that surrounds and supports the circuit board , the cover covering the circuit board with a clearance interposed between the cover and a portion of the circuit board , which includes the area, wherein the cover includes a first cover to cover a first surface of the circuit board and a second cover to cover a second surface of the circuit board , and the cover is provided, on its inner surface, with a suppression portion passing through the through-hole of the circuit board , projecting from at least one of the first cover and the second cover , and configured to suppress the inner surface from approaching the area when external pressure is applied to the cover , characterised in that the first cover is made of synthetic resin and has a circuit board attachment portion and a cable terminal cover portion integrally joined to a base end of the circuit board attachment portion , a plurality of board-resting portions which are arranged in a width direction on a surface of the circuit board attachment portion at a central portion thereof are each provided with a mounting projection , the circuit board is placed on the board-resting portions , and leading ends of the mounting projections pass through the mounting holes and are heated in a state where the leading ends project from the circuit board , and melted to cover the mounting holes and their peripheries, and the melted leading ends are then solidified to adhere to the surface of the circuit board , which faces the second cover . <EOS>