In a pantagraph type jack, a pair of side plate portions are provided at an upper end of each lower arm, and a pair of side plate portions are provided at a lower end of each upper arm, the pairs of side plate portions being superposed on each other. Outer one of the side plate portions has an insertion hole provided therein, and inner one of the side plate portions has a support sleeve portion formed thereon by burring and coaxially connected to the insertion hole and extending inwardly. The connecting shaft is formed with its outside diameter uniform over the entire axial length, and has bulged portions formed by caulking at its opposite ends inserted through the insertion holes and the support sleeve portions, which bulged portions are engaged with the outer side plate portions. In a Y-type jack, a pair of opposed side plate portions are provided at an upper end of a lower arm. A supporting sleeve portion is formed on the side plate portion by burring to extend inwardly. The connecting shaft is formed with its outside diameter uniform over the entire axial length, and has bulged portions formed by caulking at its opposite ends inserted through the insertion holes and the support sleeve portions, which bulged portions are engaged with the side plate portions.