A new IC package 12 is designed as follows. That is, a circuit block 2 is omitted from an existing IC package 11 including a package 11a having a circuit block 1 and the circuit block 2 which are connected to a plurality of terminals including high-frequency terminals, but the position of a high-frequency terminal connected to the circuit block 1 is never changed. Carried out next is omission of a portion 6, which is associated with the circuit block 2, of the package 11a. This makes it possible to provide (i) a method for designing a small IC package, and (ii) a method for manufacturing the IC package. With the methods, time required for the designing and adjustment of the designing can be shortened.