A bonded structure formed by bonding a first structure and a second structure at opposed bonding surfaces to form a microstructure or the like. At least one of the first structure and the second structure is formed of a resin composition including a polypropylene resin and a hydrogenated derivative of a block copolymer of the following general formula X-Y (X is a polymer block immiscible with the polypropylene resin, and Y is a conjugated diene elastomer polymer block). The bonding surfaces are bonded by heating an alkoxysilane or alkylsilane compound or a mixture prepared by adding a hydrogenated derivative of a block copolymer of the general formula X-Y to an alkoxysilane or alkylsilane compound applied to the bonding surface.