A process for the formation of a functional deposited film containing atoms belonging to the group III and V of the peridoical table as the main constituent atoms by introducing, into a film forming space for forming a deposited film on a substrate disposed therein, a group III compound (1) and a group IV compound (2) as the film-forming raw material and, if required, a compound (3) containing an element capable of controlling valence electrons for the deposited film as the constituent element each in a gaseous state, or in a state where at least one of such compounds is previously activated in an activation space disposed separately from the film forming space, while forming hydrogen atoms in excited state which cause chemical reaction with at least one of the compounds (1), (2) and (3) in the gaseous state or in the activated state in an activation space different from the film forming space and introducing them into the film-forming space, thereby forming the functional deposited film on the substrate, wherein the hydrogen atoms in excited state are formed from a hydrogen gas or a gas mixture composed of a hydrogen gas and a rare gas by means of a microwave plasma generated in a plasma generation chamber disposed in a cavity resonator integrated with two impedance matching circuits in a microwave circuit and the excited state of the hydrogen atom is controlled.