There are many handicapped people who need portable oxygen concentrator which operated by battery power. The weight and period of use of this product critically limit the activity range of those handicapped people. The oil-less air compressor inside of it is very critical because this compressor is the biggest power consuming part in this product. We developed miniature oil-less linear compressor with internal dynamic vibration absorber. Energy efficiency is improved by 28~38% compared with the conventional rocking piston type reciprocating compressor currently used for such products. PTFE coating for the piston and Diamond Like Carbon (DLC) coating for the cylinder were used for the better tribological properties