A solid electrolytic capacitor comprising a capacitor element including a positive electrode which contains tantalum as a principal component and is composed of a porous sintered body, a positive electrode lead which contains niobium as a principal component and has a first end part embedded in the positive electrode and a second end part extending from the positive electrode, a dielectric layer which is disposed on a surface of the positive electrode and a part of a surface of the positive electrode lead, and a negative electrode layer disposed on the dielectric layer; an positive electrode terminal electrically connected to the second end part of the positive electrode lead; a negative electrode terminal electrically connected to the negative electrode layer; and a resin outer body covering the surfaces of the capacitor element, a part of the positive electrode terminal and a part of the negative electrode terminal, wherein a linear expansion coefficient of the resin outer body is larger than all of linear expansion coefficients of the positive electrode, the positive electrode lead, the positive electrode terminal, and the negative electrode terminal.