According to the present invention, there can be provided a structure preventing the nonspecific adsorption, and a target substance-detecting element and a target substance-detecting kit. A first aspect of the present invention is a structure including: a substrate; and a membrane, present on the surface of the substrate, having a polymer of a monomer represented by the following General Formula (1) or (2): ##STR00001## (wherein R represents H or CH.sub.3; x represents an integer of 2 to 5, and y represents an integer of 1 to 7, with the proviso that x+y=an integer of 3 to 10), and ##STR00002## (wherein R.sub.1=H or CH.sub.3, and R.sub.2 represents O or NH; a represents an integer of 2 to 5, and b represents an integer of 1 to 7, with the proviso that a+b=an integer of 3 to 10.)