Pin connected link mechanism

A link mechanism usable for a variable compression ratio mechanism of an internal combustion engine includes first (11) and second (13) links pivotally connected by a pin (12) inserted through cylindrical first (21) and second pin (31) boss portions of the first (11) and second (13) links. Each of the first (21) and second (31) pin boss portions includes a circumferentially extending first narrow section (22), and a circumferentially extending first wide section (23) having an axial wall thickness greater than the axial wall thickness of the first narrow section. The wide sections (23) of the first (21) and second (31) pin boss portions are overlapped in a region extending in the axial direction of the pin (12).