Provided is a horizontal machine tool with a base frame including a base part and a saddle supporting part vertically standing on the base part; an X-axis saddle mounted on the back face of the saddle supporting part and capable of sliding in the left-right direction via an X-axis translation mechanism; a Y-axis saddle mounted on the X-axis saddle and capable of sliding in the up-down direction via a Y-axis translation mechanism; and a spindle device mounted on the Y-axis saddle and capable of sliding in the front-rear direction via a Z-axis translation mechanism. The horizontal machine tool is adapted such that a workpiece supporting member is installed on the base part in front of the saddle supporting part. This configuration can reduce the size and weight of the entire construction.