A construction machine comprising: a multi-joint front work implement that is made up of a plurality of driven members (31, 33, 35) that are joined together; a plurality of hydraulic actuators (32, 34, 36) that actuate the corresponding plurality of driven members, each based on an operation signal; an operation device (72, 73, 74) that outputs the operation signal to one of the hydraulic actuators, the one hydraulic actuator being desired by an operator, among the plurality of hydraulic actuators; a plurality of posture sensors (63, 65, 67) that detect posture information about postures of the plurality of the driven members; and a controller that carries out machine control for forcibly operating at least some of plurality of hydraulic actuators or limiting the operation of at least some of plurality of hydraulic actuators such that the front work implement operates, based on detected results from the posture sensors and predetermined conditions with respect to excavating actions entered through the operation device, the construction machine is characterized in that the controller includes: a calibration posture storing section that stores at least one predetermined calibration posture of the front work implement for calibrating the posture sensors, and a calibration posture controlling section that carries out the machine control for limiting the operation of at least some of the plurality of hydraulic actuators only in the direction in which the difference between a detection target value as a target value of the posture sensor in a predetermined calibration posture and the posture information detected by the posture sensor becomes small such that detection target values of the posture sensors in the calibration posture and the detected results from the posture sensors are equal to each other with respect to excavating actions entered through the operation device in a case where a calibration posture controlling mode is selected by the operator, and carries out the machine control to inactivate the hydraulic actuators whose detection target value of the posture sensor and the posture information detected by the posture sensor become equal to each other. a multi-joint front work implement that is made up of a plurality of driven members (31, 33, 35) that are joined together; a plurality of hydraulic actuators (32, 34, 36) that actuate the corresponding plurality of driven members, each based on an operation signal; an operation device (72, 73, 74) that outputs the operation signal to one of the hydraulic actuators, the one hydraulic actuator being desired by an operator, among the plurality of hydraulic actuators; a plurality of posture sensors (63, 65, 67) that detect posture information about postures of the plurality of the driven members; and a controller that carries out machine control for forcibly operating at least some of plurality of hydraulic actuators or limiting the operation of at least some of plurality of hydraulic actuators such that the front work implement operates, based on detected results from the posture sensors and predetermined conditions with respect to excavating actions entered through the operation device, a calibration posture storing section that stores at least one predetermined calibration posture of the front work implement for calibrating the posture sensors, and a calibration posture controlling section that carries out the machine control for limiting the operation of at least some of the plurality of hydraulic actuators only in the direction in which the difference between a detection target value as a target value of the posture sensor in a predetermined calibration posture and the posture information detected by the posture sensor becomes small such that detection target values of the posture sensors in the calibration posture and the detected results from the posture sensors are equal to each other with respect to excavating actions entered through the operation device in a case where a calibration posture controlling mode is selected by the operator, and carries out the machine control to inactivate the hydraulic actuators whose detection target value of the posture sensor and the posture information detected by the posture sensor become equal to each other.