This paper reports on impedance analyses of power distribution planes for a BGA (Ball Grid Array) . The impedance characteristics were analyzed by using simple lumped constant circuits for the power distribution plane with various power supply paths, decoupling capacitors and layer thickness between ground plane and it. The analyzed characteristics were compared with the impedance characteristics obtained from the measurement of S11. As a result, the analyzed characteristics agreed well with the measured characteristics. It is concluded that the impedance analyses using simple lumped constant circuits are effective for the estimation of impedance characteristics of power distribution planes for a BGA.