An apparatus for adjusting a length of a connecting rod of a cylinder of an internal combustion engine by installing and/or removing an intermediate plate between a connecting rod small end and a connecting rod shank of the connecting rod in the state of the connecting rod, with the following assemblies: a pivot guard for the connecting rod small end mountable to the connecting rod small end between the connecting rod small end and a cylinder liner of the cylinder; supports mountable to counterweights of the cylinder on opposite sides of the connecting rod; holders mountable to the supports and extend between the supports perpendicularly to the same; lifting cylinders mountable to the holders and lift the connecting rod small end relative to the connecting rod shank with unscrewed screw connections between connecting rod small end and connecting rod shank.