To provide a circuit board having, on a surface, a recessed part for mounting a surface mounting component, a sealing resin being efficiently supplied into the recessed part after the surface mounting component is mounted.

The recessed part 3 formed on the surface 4 of the circuit board 1 includes a main area 8 having an opening in a plane rectangular shape to be covered with the surface mounting component 2, and a first sub-area 9 having an opening extending up to a part projecting from the surface mounting component 2 while linked to the main area 8. The area of the opening of the first sub-area 9 is smaller than that of the opening of the main area 8. The recessed part 3 may further include a second sub-area, having an opening extending up to the part projecting from the surface mounting component 2 while linked to the main area 8, at a position opposed to the first sub-area 9 across the main area 8.