A spark plug comprising: an insulator including a tubular portion disposed along a center axis and having an outer circumferential surface, a leg portion smaller in outside diameter than the tubular portion and having an outer circumferential surface, and a step portion having an outer circumferential surface which connects the outer circumferential surface of the leg portion and the outer circumferential surface of the tubular portion; a center electrode disposed inside the insulator along the center axis; a tubular metallic shell including a trunk portion disposed radially outward of the tubular portion of the insulator and having an axially forward end and an inner circumferential surface, a ledge portion integral with and protruding radially inward of the axially forward end of the trunk portion with a rear end surface of the ledge portion facing the outer circumferential surface of the step portion of the insulator, and an elongated leg portion integral with the ledge portion, disposed radially outward of the leg portion of the insulator, and having an inner circumferential surface; a packing disposed between the step portion of the insulator and the ledge portion of the metallic shell, the packing including a first portion disposed between, and in contact with, the rear end surface of the ledge portion of the metallic shell and the outer circumferential surface of the step portion of the insulator, and a second portion disposed between, and in contact with, the inner circumferential surface of the trunk portion of the metallic shell and the outer circumferential surface of the tubular portion of the insulator; and a ground electrode connected to the metallic shell and facing the center electrode, wherein, in a section taken along and containing the center axis, a first axial length of the second portion of the packing as measured on the outer circumferential surface of the tubular portion of the insulator is taken from a first imaginary straight line orthogonal to the center axis and passing through a connection point between the outer circumferential surface of the tubular portion and the outer circumferential surface of the step portion of the insulator, and a second axial length of the second portion as measured on the inner circumferential surface of the trunk portion of the metallic shell is taken from the first imaginary straight line, characterized in that cutting traces (117, 119) are provided on the inner circumferential surface of the trunk portion and on the inner circumferential surface of the elongated leg portion, which are generated by cutting, by a lathe, an intermediate from which the metallic shell is made, and the first axial length is longer than the second axial length. an insulator including a tubular portion disposed along a center axis and having an outer circumferential surface, a leg portion smaller in outside diameter than the tubular portion and having an outer circumferential surface, and a step portion having an outer circumferential surface which connects the outer circumferential surface of the leg portion and the outer circumferential surface of the tubular portion; a center electrode disposed inside the insulator along the center axis; a tubular metallic shell including a trunk portion disposed radially outward of the tubular portion of the insulator and having an axially forward end and an inner circumferential surface, a ledge portion integral with and protruding radially inward of the axially forward end of the trunk portion with a rear end surface of the ledge portion facing the outer circumferential surface of the step portion of the insulator, and an elongated leg portion integral with the ledge portion, disposed radially outward of the leg portion of the insulator, and having an inner circumferential surface; a packing disposed between the step portion of the insulator and the ledge portion of the metallic shell, the packing including a first portion disposed between, and in contact with, the rear end surface of the ledge portion of the metallic shell and the outer circumferential surface of the step portion of the insulator, and a second portion disposed between, and in contact with, the inner circumferential surface of the trunk portion of the metallic shell and the outer circumferential surface of the tubular portion of the insulator; and a ground electrode connected to the metallic shell and facing the center electrode, wherein, in a section taken along and containing the center axis, a first axial length of the second portion of the packing as measured on the outer circumferential surface of the tubular portion of the insulator is taken from a first imaginary straight line orthogonal to the center axis and passing through a connection point between the outer circumferential surface of the tubular portion and the outer circumferential surface of the step portion of the insulator, and a second axial length of the second portion as measured on the inner circumferential surface of the trunk portion of the metallic shell is taken from the first imaginary straight line, characterized in that cutting traces (117, 119) are provided on the inner circumferential surface of the trunk portion and on the inner circumferential surface of the elongated leg portion, which are generated by cutting, by a lathe, an intermediate from which the metallic shell is made, and the first axial length is longer than the second axial length.