To make the soldering conditions of electrodes of a leadless HEMT visually checkable.

Through-holes 5 are formed in microstriplines 2, 3 and a ground pattern 4 (foot pattern) on a board for soldering electrodes G, D, S of an HEMT, and solder deposited to the HEMT electrodes is made to flow into each through-hole to make the soldering condition of each electrode checkable, by seeing the through-hole from the backside of the board. Since inductance components are formed resulting from the through-holes, chip capacitors are connected between a land pattern of the through-holes of the electrodes G, D, and the ground pattern on the board backside, or the land pattern is formed on an open stub to form LPFs or traps with the inductance components, thereby preventing deterioration of the impedance characteristics or abnormal oscillations.