A method of producing a functional device which comprises forming a functional layer containing an organic material, an electrode layer and an insulating layer on a substrate, wherein the step of forming the insulating layer is effected with a temperature T of the substrate being controlled to satisfy the following relationship: T.ltoreq.Tg.times.(.DELTA.E2/.DELTA.E1) where Tg is a glass transition temperature of the organic material, .DELTA.E1 is an activation energy for crystallization of the organic material measured while the electrode layer and the insulating layer are not stacked on the functional layer and .DELTA.E2 is an activation energy for crystallization of the organic material while the electrode layer is formed on the functional layer.