A construction machine comprising: a multipoint type front work implement that is configured by coupling a plurality of driven members including a work tool and that is supported by a machine body of the construction machine in such a manner as to be rotatable in a perpendicular direction; posture information sensors that detect posture information about the plurality of driven members; and a front posture computing device (15a, 15A) that computes a posture of the multipoint type front work implement on the basis of detection information from the posture information sensors, a machine body sloping detection sensor that detects a slope angle of the machine body with respect to a horizontal surface, an action of the multipoint type front work implement being controlled on the basis of the posture of the front work implement computed by the front posture computing device (15a, 15A), characterized in that the front posture computing device (15a, 15A) includes a reference position setting section that sets a reference plane parallel to the horizontal surface as reference position specified relatively to the machine body; a sloping reference plane computing section that computes a sloping reference plane obtained by sloping the reference plane on the basis of the slope angle of the machine body detected by the machine body sloping detection section; a calibration value computing section that computes calibration parameters used in calibration of the detection information from the posture information sensors; and a work position computing section that computes a relative position of the work tool to the machine body on the basis of the detection information from the posture information sensors and a computation result of the calibration value computing section, and the calibration value computing section computes the calibration parameters on the basis of the detection information from the posture information sensors in a plurality of postures of the front work implement in which a reference point set on any of the plurality of driven members in advance matches any of positions on the reference plane set by the sloping reference plane computing section, which differ in a posture of at least one of the plurality of driven members, and the number of which corresponds to the number of the driven members. a multipoint type front work implement that is configured by coupling a plurality of driven members including a work tool and that is supported by a machine body of the construction machine in such a manner as to be rotatable in a perpendicular direction; posture information sensors that detect posture information about the plurality of driven members; and a front posture computing device (15a, 15A) that computes a posture of the multipoint type front work implement on the basis of detection information from the posture information sensors, a machine body sloping detection sensor that detects a slope angle of the machine body with respect to a horizontal surface, an action of the multipoint type front work implement being controlled on the basis of the posture of the front work implement computed by the front posture computing device (15a, 15A), characterized in that the front posture computing device (15a, 15A) includes a reference position setting section that sets a reference plane parallel to the horizontal surface as reference position specified relatively to the machine body; a sloping reference plane computing section that computes a sloping reference plane obtained by sloping the reference plane on the basis of the slope angle of the machine body detected by the machine body sloping detection section; a calibration value computing section that computes calibration parameters used in calibration of the detection information from the posture information sensors; and a work position computing section that computes a relative position of the work tool to the machine body on the basis of the detection information from the posture information sensors and a computation result of the calibration value computing section, and the calibration value computing section computes the calibration parameters on the basis of the detection information from the posture information sensors in a plurality of postures of the front work implement in which a reference point set on any of the plurality of driven members in advance matches any of positions on the reference plane set by the sloping reference plane computing section, which differ in a posture of at least one of the plurality of driven members, and the number of which corresponds to the number of the driven members.