The present invention relates to a maintenance apparatus for a shock absorber of a landing gear, comprising a liquid reservoir which can be connected to an interior space of the shock absorber via a liquid line, a gas reservoir which can be connected to the interior space via a gas line, a coupling member for sealingly coupling the liquid reservoir and the gas reservoir, wherein the maintenance apparatus is configured to allow an exchange to occur of liquid and gas between the liquid reservoir and gas reservoir, respectively, and the interior space, the maintenance apparatus comprising control means for determining that a partial volume of the interior space occupied by the gas reaches a reference level as a result of the exchange and for bringing the partial volume of the interior space of the shock absorber respectively occupied by the gas and the liquid to a target level. The invention also relates to a maintenance method.