A technique of easy manufacture of a column and a bed of a machine tool in a short time is provided by having an assembly structure of sheet metal members. A column body of the machine tool is constituted by combining a front member with a rear member 130 and mounting a side cover. Its inside is reinforced by a plurality of ribs 150, 160. Each of the members is made by precision laser machining of sheet plate materials. The column body is assembled by inserting projection portions provided on one member into slits formed on the other member.