A joint structure for a composite member made from a fiber-reinforced composite material having a fiber as a reinforcing material and a resin as a matrix material selected from the group consisting of carbon fiber reinforced plastic, glass fiber reinforced plastic, boron fiber reinforced plastic and aramid fiber reinforced plastic, comprising: a plate for increasing thickness (40a, 40b) adhered to at least one side of the composite member; wherein the composite member and a counterpart member are fastened together by inserting and fixing a plurality of fastener members (30a-30d) into a plurality of through-holes (24, 26a, 26b) formed through the composite member, the plate for increasing thickness (40a, 40b), and the counterpart member to be joined to the composite member, the joint structure is configured so that a shear force acts between the composite member and the counterpart member, and the plurality of fastener members (30a-30d) is disposed along a direction of action of the shear force, characterized in that the plate for increasing thickness (40a, 40b) is made from a metal material selected from the group consisting of titanium alloy, high nickel alloy or cobalt alloy or made from a polycarbonate resin-based material having a ductility higher than the composite member, each of the through-holes formed through the composite member having a diameter larger than a diameter of the through-hole formed through the plate for increasing thickness (40a, 40b) and the counterpart member, so that the joint structure is configured to resist shear load by the plate for increasing thickness (40a, 40b) without bringing the composite member into contact with the plurality of fastener members (30a-30d), and wherein a plate for increasing thickness (40a, 40b) is adhered to each of both sides of the composite member. a plate for increasing thickness (40a, 40b) adhered to at least one side of the composite member; wherein the composite member and a counterpart member are fastened together by inserting and fixing a plurality of fastener members (30a-30d) into a plurality of through-holes (24, 26a, 26b) formed through the composite member, the plate for increasing thickness (40a, 40b), and the counterpart member to be joined to the composite member, the joint structure is configured so that a shear force acts between the composite member and the counterpart member, and the plurality of fastener members (30a-30d) is disposed along a direction of action of the shear force, characterized in that the plate for increasing thickness (40a, 40b) is made from a metal material selected from the group consisting of titanium alloy, high nickel alloy or cobalt alloy or made from a polycarbonate resin-based material having a ductility higher than the composite member, each of the through-holes formed through the composite member having a diameter larger than a diameter of the through-hole formed through the plate for increasing thickness (40a, 40b) and the counterpart member, so that the joint structure is configured to resist shear load by the plate for increasing thickness (40a, 40b) without bringing the composite member into contact with the plurality of fastener members (30a-30d), and