The present invention provides a bottom layer film of a self-organizing film that forms a vertical pattern in the self-organizing film without causing intermixing (layer mixing) with a top-layer self-organizing film. This bottom layer film-formation composition of a self-organizing film is characterized by containing a polymer having at least 0.2 mol% of a unit structure of a polycyclic aromatic vinyl compound with respect to all the unit structures of the polymer. The polymer has at least 20 mol% of a unit structure of an aromatic vinyl compound with respect to all the unit structures of the polymer, and has at least 1 mol% of a unit structure of a polycyclic aromatic vinyl compound with respect to all of the unit structures of aromatic vinyl compound. The aromatic vinyl compound contains vinylnaphthylene, acenaphthylene, or vinylcarbazole, which each may be substituted, and the polycyclic aromatic vinyl compound is vinylnaphthlylene, acenaphthylene, or vinylcarbazole. Also, the aromatic vinyl compound contains vinylnaphthylene, acenaphthylene, or vinylcarbazole, which each may be substituted, and an optionally substituted styrene, and the polycyclic aromatic vinyl compound is vinylnaphthlylene, acenaphthylene, or vinylcarbazole.