To obtain a mounting form suppressed in the characteristic deterioration of a flip-chip mounted semiconductor chip without using a radio wave absorber.

Unwanted radiation in flip-chip mounting is reflected and generated by a characteristic impedance discontinuous portion of a transmission line. Its cause results form a structure having an intermittent shape of the transmission line, a parasitic capacitance pattern generated by an unnecessary conductor extending from a GND conductor equivalent to an open stab, and a GND pattern corresponding to a λ/2 wavelength of a millimeter wave signal. A line transformer is obtained where characteristic impedance is continuously changed from a microstrip line to a coplanar line for a conductor pattern using a taper or a curved line. A multilayer substrate is used for a circuit substrate. In the coplanar line, it is important to concentrate an electromagnetic wave component of the millimeter wave signal between gaps of the coplanar line. Therefore, a release pattern is formed at a grounding lower electrode, thereby suppressing unwanted radiation.