A grinder with built-in grinding agent dispenser includes a driving shank having an adapter end for operatively coupling with a grinder machine for being driven to rotate, a grinding shaft operatively coupling with the driving shank for being driven to rotate, an abrasive arrangement provided at the grinding shaft for refining a surface of a workpiece, and a grinding agent dispenser built-in within the grinder for guiding a flow of grinding agent. The dispenser has a supplying channel connected to a supplying inlet, and a grinding channel connected to a dispensing outlet and communicatively connected to the supplying channel, wherein the supplying channel and the grinding channel are provided within the driving shank and the grinding shaft, so that when the grinding agent is feeding into the supplying channel via the supplying inlet, the grinding agent is guided to flow to the dispensing outlet, so as to disperse grinding agent.