A construction machine, comprising: a lower traveling body; an upper slewing body installed on the lower traveling body so as to be slewable; a tank which stores hydraulic fluid; a hydraulic pump which discharges hydraulic fluid from the tank; a working attachment attached to the upper slewing body and having a boom, an arm attached to a leading end of the boom, a working device attached to a leading end of the arm, a boom cylinder which actuates the boom, an arm cylinder which actuates the arm, and a working cylinder which actuates the working device, at least one cylinder of the arm cylinder and the working cylinder which are positioned closer to a leading end of the working attachment than the boom cylinder being a fluid-supplied cylinder (7, 8) which receives a supply of hydraulic fluid from the hydraulic pump, together with the boom cylinder, the attachment being arranged so as to receive a reaction force during work involving extension of the fluid-supplied cylinder (7, 8), the reaction force acting in a direction of raising the boom to thereby increase a rod-side pressure of the boom cylinder and reduce a head-side pressure thereof; a first operation device which is operated to move the boom cylinder; a second operation device which is operated to move the fluid-supplied cylinder (7, 8); a first control valve which operates in response to the operation of the first operation device to control a motion of the boom cylinder; a second control valve which operates in response to the operation of the second operation device to control a motion of the fluid-supplied cylinder (7, 8); characterized by a flow-rate-limiting section which limits a supply flow rate from the hydraulic pump to a head-side fluid chamber of the boom cylinder, only when an operation for raising the boom is performed in a situation where the rod-side pressure of the boom cylinder is higher than the head-side pressure thereof; and an anti-cavitation circuit for replenishing the head-side fluid chamber of the boom cylinder with hydraulic fluid from the tank. a lower traveling body; an upper slewing body installed on the lower traveling body so as to be slewable; a tank which stores hydraulic fluid; a hydraulic pump which discharges hydraulic fluid from the tank; a working attachment attached to the upper slewing body and having a boom, an arm attached to a leading end of the boom, a working device attached to a leading end of the arm, a boom cylinder which actuates the boom, an arm cylinder which actuates the arm, and a working cylinder which actuates the working device, at least one cylinder of the arm cylinder and the working cylinder which are positioned closer to a leading end of the working attachment than the boom cylinder being a fluid-supplied cylinder (7, 8) which receives a supply of hydraulic fluid from the hydraulic pump, together with the boom cylinder, the attachment being arranged so as to receive a reaction force during work involving extension of the fluid-supplied cylinder (7, 8), the reaction force acting in a direction of raising the boom to thereby increase a rod-side pressure of the boom cylinder and reduce a head-side pressure thereof; a first operation device which is operated to move the boom cylinder; a second operation device which is operated to move the fluid-supplied cylinder (7, 8); a first control valve which operates in response to the operation of the first operation device to control a motion of the boom cylinder; a second control valve which operates in response to the operation of the second operation device to control a motion of the fluid-supplied cylinder (7, 8); characterized by a flow-rate-limiting section which limits a supply flow rate from the hydraulic pump to a head-side fluid chamber of the boom cylinder, only when an operation for raising the boom is performed in a situation where the rod-side pressure of the boom cylinder is higher than the head-side pressure thereof; and an anti-cavitation circuit for replenishing the head-side fluid chamber of the boom cylinder with hydraulic fluid from the tank.