A biosensor chip is constituted by: a substrate; a metal film which is physically attached to the substrate; and a self assembled monolayer constituted by alkyl chains, which is physically attached to the metal film. Ligands and at least one functional group, selected from a group consisting of a hydroxyl group, a carboxyl group, an alkoxy group, a methyl group, and hydrogen atoms are physically attached to the self assembled monolayer. The ratio between the total number of alkyl chains physically attached to the metal film and the number of alkyl chains which are covalently bonded with the ligands is within a range of 0.40 to 0.99.