A regeneration device for an exhaust-gas purifying device which is provided in an exhaust system of an internal combustion engine, the regeneration device comprising: an injector for injecting fuel into a cylinder of the internal combustion engine; a glow plug which is energized to be heated to increase a temperature inside the cylinder; a regeneration control device for executing a regenerating operation for restoring a purification capacity of the exhaust-gas purifying device by controlling the injection of fuel of the injector and the energization of the glow plug, wherein during the regenerating operation, the regeneration control device controls the injection of fuel of the injector by a multi-stage injection including at least a post injection and energizes the glow plug at a predetermined duty ratio to burn, within the cylinder, fuel supplied by the post injection, wherein the regeneration device further comprises: an operating state detecting device (31, 32) for detecting an operating state of the internal combustion engine; and an energization amount map in which the duty ratio of the glow plug is set so as to increase more as the operating state of the internal combustion engine lowers, wherein the regeneration control device sets the duty ratio at which the glow plug is energized by referring to the energization amount map based on the operating state detected by the operating state detecting device, characterized in that the regeneration device further comprises: a cylinder pressure sensor for detecting a pressure inside the cylinder; an estimating device for estimating an actual heat generation rate of the post injection based on a detection value of the cylinder pressure sensor; and a learning correction device for executing a learning correction operation of the duty ratio of the energization amount map based on a difference (ΔQ) between the actual heat generation rate estimated by the estimating device and a predetermined target heat generation rate. an injector for injecting fuel into a cylinder of the internal combustion engine; a glow plug which is energized to be heated to increase a temperature inside the cylinder; a regeneration control device for executing a regenerating operation for restoring a purification capacity of the exhaust-gas purifying device by controlling the injection of fuel of the injector and the energization of the glow plug, wherein during the regenerating operation, the regeneration control device controls the injection of fuel of the injector by a multi-stage injection including at least a post injection and energizes the glow plug at a predetermined duty ratio to burn, within the cylinder, fuel supplied by the post injection, wherein the regeneration device further comprises: an operating state detecting device (31, 32) for detecting an operating state of the internal combustion engine; and an energization amount map in which the duty ratio of the glow plug is set so as to increase more as the operating state of the internal combustion engine lowers, an operating state detecting device (31, 32) for detecting an operating state of the internal combustion engine; and an energization amount map in which the duty ratio of the glow plug is set so as to increase more as the operating state of the internal combustion engine lowers, wherein the regeneration control device sets the duty ratio at which the glow plug is energized by referring to the energization amount map based on the operating state detected by the operating state detecting device, characterized in that the regeneration device further comprises: a cylinder pressure sensor for detecting a pressure inside the cylinder; an estimating device for estimating an actual heat generation rate of the post injection based on a detection value of the cylinder pressure sensor; and a learning correction device for executing a learning correction operation of the duty ratio of the energization amount map based on a difference (ΔQ) between the actual heat generation rate estimated by the estimating device and a predetermined target heat generation rate. a cylinder pressure sensor for detecting a pressure inside the cylinder; an estimating device for estimating an actual heat generation rate of the post injection based on a detection value of the cylinder pressure sensor; and a learning correction device for executing a learning correction operation of the duty ratio of the energization amount map based on a difference (ΔQ) between the actual heat generation rate estimated by the estimating device and a predetermined target heat generation rate.