An output characteristic changing system for a construction machine comprising a control device that controls equipment (8, 10, 12) for driving an actuator (2B, 3B, 4D, 4E, 4F) in the construction machine and can change an output characteristic of said actuator (2B, 3B, 4D, 4E, 4F) incorporated in said control device to be adjusted to each of operators of said construction machine, wherein a management server is provided in a position away from said construction machine, characterised in that, said management server includes: a server-side memory part that stores operator information assigned to each of the operators of said construction machine, vehicle body information assigned to respective construction machines, and output characteristic information of said actuator (2B, 3B, 4D, 4E, 4F) in such a manner as to be associated with operability desired by each of said operators; an information extraction part that, in a case where said operator information and said vehicle body information are transmitted from said control device in said construction machine, extracts said output characteristic information in conformity with the operability desired by said operator from said operator information and said vehicle body information from said server-side memory part; and a server-side transmission part that transmits said output characteristic information extracted from said information extraction part toward said control device in said construction machine, said output characteristic information that is stored in said server-side memory part in said management server being information including at least one of an output characteristic corresponding to a control parameter for use in control of said equipment (8, 10, 12) for driving said actuator (2B, 3B, 4D, 4E, 4F) and an output characteristic corresponding to a function setting of said construction machine. a server-side memory part that stores operator information assigned to each of the operators of said construction machine, vehicle body information assigned to respective construction machines, and output characteristic information of said actuator (2B, 3B, 4D, 4E, 4F) in such a manner as to be associated with operability desired by each of said operators; an information extraction part that, in a case where said operator information and said vehicle body information are transmitted from said control device in said construction machine, extracts said output characteristic information in conformity with the operability desired by said operator from said operator information and said vehicle body information from said server-side memory part; and a server-side transmission part that transmits said output characteristic information extracted from said information extraction part toward said control device in said construction machine, said output characteristic information that is stored in said server-side memory part in said management server being information including at least one of an output characteristic corresponding to a control parameter for use in control of said equipment (8, 10, 12) for driving said actuator (2B, 3B, 4D, 4E, 4F) and an output characteristic corresponding to a function setting of said construction machine.