An adhesive comprising: a multivalent vinyl ether compound; a compound including two or more of a constitutional unit represented by Formula (b); and a thermoplastic resin, Formula (b) expressed as follows: wherein Z 1 represents a group resulting from removing (n 1 + 2) hydrogen atoms from a structural formula of a compound selected from a saturated or unsaturated aliphatic hydrocarbon, a saturated or unsaturated alicyclic hydrocarbon, an aromatic hydrocarbon, a heterocyclic compound, and a compound including two or more of these compounds bonded to each other through a single bond or a linkage group; X is, independently in each occurrence, selected from hydroxy and carboxy; and n 1 represents an integer of 1 or more, where n 1 occurrences of X may be identical to or different from each other, wherein the compound has a weight-average molecular weight of 1500 or more and the thermoplastic resin has a weight-average molecular weight of 1500 or more, both determined by GPC and calibrated with a polystyrene standard, wherein the thermoplastic resin is at least one compound selected from the group consisting of: poly(vinyl acetal) resins; polyester resins; polyurethane resins; and polyamide resins, wherein the polyester resins comprise at least one compound selected from the group consisting of polyesters resulting from polycondensation of a diol component and a dicarboxylic acid component, polyesters resulting from polycondensation of a hydroxycarboxylic acid, polyesters resulting from ring-opening polymerization of a lactone, and urethane-bond-containing polyesters resulting from reaction of a polyester diol with a diisocyanate, and wherein the polyamide resins comprise at least one compound selected from the group consisting of polyamides resulting from polycondensation of a diamine component with a dicarboxylic acid component, polyamides resulting from polycondensation of an aminocarboxylic acid, polyamides resulting from ring-opening polymerization of a lactam, and polyesteramides resulting from polycondensation of a diamine component with a dicarboxylic acid component and a diol component. a multivalent vinyl ether compound; a compound including two or more of a constitutional unit represented by Formula (b); and a thermoplastic resin, wherein Z 1 represents a group resulting from removing (n 1 + 2) hydrogen atoms from a structural formula of a compound selected from a saturated or unsaturated aliphatic hydrocarbon, a saturated or unsaturated alicyclic hydrocarbon, an aromatic hydrocarbon, a heterocyclic compound, and a compound including two or more of these compounds bonded to each other through a single bond or a linkage group; X is, independently in each occurrence, selected from hydroxy and carboxy; and n 1 represents an integer of 1 or more, where n 1 occurrences of X may be identical to or different from each other, wherein the compound has a weight-average molecular weight of 1500 or more and the thermoplastic resin has a weight-average molecular weight of 1500 or more, both determined by GPC and calibrated with a polystyrene standard, wherein the thermoplastic resin is at least one compound selected from the group consisting of: poly(vinyl acetal) resins; polyester resins; polyurethane resins; and polyamide resins, poly(vinyl acetal) resins; polyester resins; polyurethane resins; and polyamide resins, wherein the polyester resins comprise at least one compound selected from the group consisting of polyesters resulting from polycondensation of a diol component and a dicarboxylic acid component, polyesters resulting from polycondensation of a hydroxycarboxylic acid, polyesters resulting from ring-opening polymerization of a lactone, and urethane-bond-containing polyesters resulting from reaction of a polyester diol with a diisocyanate, and wherein the polyamide resins comprise at least one compound selected from the group consisting of polyamides resulting from polycondensation of a diamine component with a dicarboxylic acid component, polyamides resulting from polycondensation of an aminocarboxylic acid, polyamides resulting from ring-opening polymerization of a lactam, and polyesteramides resulting from polycondensation of a diamine component with a dicarboxylic acid component and a diol component.