<p>The present invention relates to a multi-stage variable reciprocating pump of the inlet pressure forming the inside of a main cylinder to have multi stages where a main piston is reciprocating without extra vibrators to be able to periodically change the applied pressure size in the reciprocating pump. To achieve this, the reciprocating pump includes: a cylindrical main cylinder; a main piston reciprocating in a lengthwise direction in a closing state of the cross-section of the main cylinder inside the same; variable cross-section auxiliary pistons integrally and respectively arranged on both sides of the main piston; and pressure applying piston extended in the lengthwise direction from each variable section auxiliary piston, and directly applying the pressure to an object to be applied with a grout material.</p>
