A one-part moisture-curable polyurethane composition of the present technology comprises: a preliminary composition containing a urethane prepolymer (A); and an adhesion promoter (B); the adhesion promoter being a reaction product of a compound (b1) having three or more isocyanate groups; and a compound (b2) of at least one type of a compound selected from the group consisting of compounds represented by Formula (1) to (4) described below and hydrogenated compounds of compounds represented by Formula (1) to (3) described below; wherein a ratio (NCO/OH) between an isocyanate group (NCO) of the compound (b1) and a hydroxy group (OH) of the compound (b2) is 1.2 to 3.2; and a content of the adhesion promoter (B) being 0.1 to 10 parts by mass per 100 parts by mass of the preliminary composition.