An exhaust muffler including a tail pipe comprising: a chamber provided in the middle of an exhaust pipe for an internal combustion engine; and a tail pipe which is connected to an end portion of an exhaust opening of the exhaust pipe and in which a plurality of fins are disposed inside thereof in a spiral shape gradually widening toward a discharging direction of exhaust gas, wherein: the chamber comprises a cover body surrounding a periphery of a side surface of the exhaust pipe and an internal exhaust pipe in which a plurality of diffusion holes are drilled on the side surface of the exhaust pipe surrounded by the cover body; the internal exhaust pipe comprises a diffusion exhaust pipe having a wide bore, which is provided on an inlet side of the exhaust gas and a compression exhaust pipe having a narrow bore, which is provided on an outlet side of the exhaust gas; and the diffusion holes are drilled in a portion of the side surface of the internal exhaust pipe, characterized in that: in the chamber, the diffusion exhaust pipe and the compression exhaust pipe are connected in series with each other, and a partition plate bisecting the inside of the diffusion exhaust pipe and the compression exhaust pipe in the longitudinal direction is formed; and the diffusion holes are drilled to be distributed on symmetrical positions in a range of 30 to 60% of the periphery of the internal exhaust pipe in respect of the partition plate through the peripheral surface of the diffusion exhaust pipe to increase fuel efficiency. a chamber provided in the middle of an exhaust pipe for an internal combustion engine; and a tail pipe which is connected to an end portion of an exhaust opening of the exhaust pipe and in which a plurality of fins are disposed inside thereof in a spiral shape gradually widening toward a discharging direction of exhaust gas, wherein: the chamber comprises a cover body surrounding a periphery of a side surface of the exhaust pipe and an internal exhaust pipe in which a plurality of diffusion holes are drilled on the side surface of the exhaust pipe surrounded by the cover body; the internal exhaust pipe comprises a diffusion exhaust pipe having a wide bore, which is provided on an inlet side of the exhaust gas and a compression exhaust pipe having a narrow bore, which is provided on an outlet side of the exhaust gas; and the diffusion holes are drilled in a portion of the side surface of the internal exhaust pipe, characterized in that: in the chamber, the diffusion exhaust pipe and the compression exhaust pipe are connected in series with each other, and a partition plate bisecting the inside of the diffusion exhaust pipe and the compression exhaust pipe in the longitudinal direction is formed; and the diffusion holes are drilled to be distributed on symmetrical positions in a range of 30 to 60% of the periphery of the internal exhaust pipe in respect of the partition plate through the peripheral surface of the diffusion exhaust pipe to increase fuel efficiency. the chamber comprises a cover body surrounding a periphery of a side surface of the exhaust pipe and an internal exhaust pipe in which a plurality of diffusion holes are drilled on the side surface of the exhaust pipe surrounded by the cover body; the internal exhaust pipe comprises a diffusion exhaust pipe having a wide bore, which is provided on an inlet side of the exhaust gas and a compression exhaust pipe having a narrow bore, which is provided on an outlet side of the exhaust gas; and the diffusion holes are drilled in a portion of the side surface of the internal exhaust pipe, characterized in that: in the chamber, the diffusion exhaust pipe and the compression exhaust pipe are connected in series with each other, and a partition plate bisecting the inside of the diffusion exhaust pipe and the compression exhaust pipe in the longitudinal direction is formed; and the diffusion holes are drilled to be distributed on symmetrical positions in a range of 30 to 60% of the periphery of the internal exhaust pipe in respect of the partition plate through the peripheral surface of the diffusion exhaust pipe to increase fuel efficiency. in the chamber, the diffusion exhaust pipe and the compression exhaust pipe are connected in series with each other, and a partition plate bisecting the inside of the diffusion exhaust pipe and the compression exhaust pipe in the longitudinal direction is formed; and the diffusion holes are drilled to be distributed on symmetrical positions in a range of 30 to 60% of the periphery of the internal exhaust pipe in respect of the partition plate through the peripheral surface of the diffusion exhaust pipe to increase fuel efficiency.