A spark plug, comprising: a spark plug main body including a cylindrical metal shell, a cylindrical insulator accommodated in the metal shell, a center electrode extending in an axial direction and accommodated in the insulator, and a ground electrode having one end that is joined to an end portion of the metal shell and the other end that is disposed so as to form a gap with a front end portion of the center electrode, wherein the spark plug main body is adapted to be fixed to an internal-combustion engine using a cylindrical pressing member that has a tool engagement portion in an upper portion and a male thread formed on an outer circumferential face of the pressing member for engaging with a female thread of the plug hole of an internal-combustion engine, and wherein a removing-tool engagement portion for engaging with a tool for removing the spark plug main body from the internal-combustion engine is formed on an outer face of an other end portion of the metal shell; wherein the metal shell includes: a caulking portion formed in the other end portion of the metal shell and holding the insulator therein by caulking; a buckling portion formed toward the one end portion of the metal shell with respect to the caulking portion and adapted to be simultaneously deformed along with the caulking portion; and a thick portion formed between the caulking portion and the buckling portion and being thicker than the caulking portion and the buckling portion, wherein the removing-tool engagement portion is formed in the thick portion; and wherein the removing-tool engagement portion is configured to enable applying an axial force to the spark plug. a spark plug main body including a cylindrical metal shell, a cylindrical insulator accommodated in the metal shell, a center electrode extending in an axial direction and accommodated in the insulator, and a ground electrode having one end that is joined to an end portion of the metal shell and the other end that is disposed so as to form a gap with a front end portion of the center electrode, wherein the spark plug main body is adapted to be fixed to an internal-combustion engine using a cylindrical pressing member that has a tool engagement portion in an upper portion and a male thread formed on an outer circumferential face of the pressing member for engaging with a female thread of the plug hole of an internal-combustion engine, and wherein a removing-tool engagement portion for engaging with a tool for removing the spark plug main body from the internal-combustion engine is formed on an outer face of an other end portion of the metal shell; wherein the metal shell includes: a caulking portion formed in the other end portion of the metal shell and holding the insulator therein by caulking; a buckling portion formed toward the one end portion of the metal shell with respect to the caulking portion and adapted to be simultaneously deformed along with the caulking portion; and a thick portion formed between the caulking portion and the buckling portion and being thicker than the caulking portion and the buckling portion, a caulking portion formed in the other end portion of the metal shell and holding the insulator therein by caulking; a buckling portion formed toward the one end portion of the metal shell with respect to the caulking portion and adapted to be simultaneously deformed along with the caulking portion; and a thick portion formed between the caulking portion and the buckling portion and being thicker than the caulking portion and the buckling portion, wherein the removing-tool engagement portion is formed in the thick portion; and wherein the removing-tool engagement portion is configured to enable applying an axial force to the spark plug.