In a reliability-improving structure of a reciprocating compressor, by minimizing vibration noise occurred in operation, adjusting a quantity of compression gas accurately, measuring an air gap in order to uniform an air gap of a reciprocating motor in an assembly process and firming combination between an inner stator combined with a piston for compressing gas so as to perform a linear reciprocating motion with the piston and a magnet fixedly combined with the inner stator, reliability of a reciprocating compressor can be improved.