A film formation method, in a vertical batch CVD apparatus, is preset to repeat a cycle a plurality of times to laminate thin films formed by respective times. The cycle alternately includes an adsorption step of adsorbing a source gas onto a surface of the target substrates and a reaction step of causing a reactive gas to react with the adsorbed source gas. The adsorption step is arranged to make a plurality of times a supply sub-step of performing supply of the source gas to the process field with an intermediate sub-step of stopping supply of the source gas to the process field interposed therebetween, while maintaining a shut-off state of supply of the reactive gas. The reaction step is arranged to continuously perform supply of the reactive gas to the process field, while maintaining a shut-off state of supply of the source gas.