Disclosed is a multilayer organic solar cell having a structure wherein an inter-layer (3) is arranged between a first photoactive layer (1) and a second photoactive layer (2). This structure is obtained by forming the inter-layer (3) on the first photoactive layer (1) which is formed from an organic compound solution containing a donor material and an acceptor material, and then applying an organic compound solution containing a donor material and an acceptor material over the inter-layer (3) for forming the second photoactive layer (2). The inter-layer (3) is composed of at least either of a transparent oxide and a transparent nitride. By having such a structure, the inter-layer (3) prevents the solvent in the solution for the second photoactive layer (2) from permeating into the first photoactive layer (1) when the second photoactive layer (2) is formed over the first photoactive layer (1) by applying the solution. Consequently, the first photoactive layer (1) is prevented from destruction or deterioration in functions.