A contact pin to electrically connect a first electrical component to a second electrical component and contact with the first and second electrical components at a sufficiently large contact pressure. The contact pin includes a first plunger with a first contact portion and a second plunger with a second contact portion. An expandable meander portion is formed on the second plunger. A contact piece to conduct electricity between the first and second plungers is provided to guide the expanding and shrinking operation of the meander portion. The first and second plungers are conducted via the contact piece when the first electrical component is electrically connected to the second electrical component, and the meander portion is shrunk to bring the first contact portion of the first plunger and the second contact portion of the second plunger into contact with the first and second electrical components at a sufficiently large contact pressure.