To provide an apparatus capable of forming a high-quality deposited film with a high productivity; and a method using the same.

The apparatus forms a deposited film on a plurality of grounded substrates in a reactor. At the periphery of each of the substrates, a plurality of high-frequency electrodes arranged nearest to the substrates are present; and at least one of the high-frequency electrodes is arranged so as to be surrounded by the substrates. In the relationship between the substrates and the high-frequency electrodes, the surface area ratio among the high-frequency electrodes is determined so that when the value of high-frequency electric power supplied by a high-frequency electric source is increased, the value of high-frequency electric power, at which the proportional relationship between the value of high-frequency electric power and the deposited-film forming speed of a part of the substrates facing the high-frequency electrodes is lost, becomes equal among the high-frequency electrodes.