INTERNAL COMBUSTION ENGINE

An internal combustion engine includes a cylinder block (2), a cylinder liner (5), a piston (6), and a piston ring (18). The cylinder liner (5) has a cylindrical shape, and is provided inside the cylinder block (2). The piston (6) is positioned inside the cylinder liner (5). The piston (6) includes a ring groove (14) and a top land (15). The ring groove (14) is positioned on an outer periphery of the piston (6) in the vicinity of the top land (15). The piston ring (18) is arranged inside the ring groove (14). The cylinder liner (5) includes a first portion (30) and a second portion. The first portion (30) is positioned at least in a part of an inner periphery (5a) of the cylinder liner (5), which faces the top land (15) of the piston (6) when the piston (6) is at a top dead center. The first portion (30) includes a first inner periphery (30a). The first inner periphery (30a) has a first radius. The second portion includes a second inner periphery (5a). The second inner periphery (5a) has a second radius. The first radius is larger than the second radius by 100 µm to 1000 µm.