A long leg fixing device for a table, the table having four long legs and having a structure in which two of the long legs are linked by means of a crossbeam portion, and in which said two long legs are fitted to the table in such a way as to be capable of pivoting by means of a hinge to move together to open and close the long legs, the long leg fixing device comprising: a base that is fixable to a top plate of the table; an arm pin inserted into said base; an arm and a lever arranged to swing around the arm pin, said lever having a claw portion; a cam pin inserted through said arm and said lever and which is not inserted into the base, said cam pin being a common shaft for said arm and said lever; a lever cam arranged to swing around said cam pin as a shaft and arranged to engage with the claw portion of the lever, the lever cam including a hanging plate portion in the center thereof; a latch; a link plate including a base portion and a claw portion arranged to interlock with the latch; a seat portion which is mountable to the crossbeam portion of the table, the arm and the latch being configured to grip the seat portion; and, a latch receiver and a push plate arranged inside the latch, and a latch spring is arranged in a space surrounded by the latch receiver and the push plate; wherein the diameter of a pin hole of the lever cam through which said cam pin is inserted is formed to be slightly larger than the diameter of a body portion of said cam pin, and a pin hole of said lever is formed in the shape of a slot; wherein the lever is operable to cause the hanging plate portion to come into contact with the base portion of the link plate and to cause the claw portion of the link plate to interlock with the latch, such that the arm and the latch are interlocked and the link plate is moved in the direction of the lever; wherein the latch spring is a compression coil spring, which is locked to the base portion of the latch receiver and the spring receiver portion of the latch, and always urges the latch and the latch receiver; and wherein the lever cam that engages with the claw portion of the lever swings around the cam pin in response to the swing of the lever. a base that is fixable to a top plate of the table; an arm pin inserted into said base; an arm and a lever arranged to swing around the arm pin, said lever having a claw portion; a cam pin inserted through said arm and said lever and which is not inserted into the base, said cam pin being a common shaft for said arm and said lever; a lever cam arranged to swing around said cam pin as a shaft and arranged to engage with the claw portion of the lever, the lever cam including a hanging plate portion in the center thereof; a latch; a link plate including a base portion and a claw portion arranged to interlock with the latch; a seat portion which is mountable to the crossbeam portion of the table, the arm and the latch being configured to grip the seat portion; and, a latch receiver and a push plate arranged inside the latch, and a latch spring is arranged in a space surrounded by the latch receiver and the push plate; wherein the diameter of a pin hole of the lever cam through which said cam pin is inserted is formed to be slightly larger than the diameter of a body portion of said cam pin, and a pin hole of said lever is formed in the shape of a slot; wherein the lever is operable to cause the hanging plate portion to come into contact with the base portion of the link plate and to cause the claw portion of the link plate to interlock with the latch, such that the arm and the latch are interlocked and the link plate is moved in the direction of the lever; wherein the latch spring is a compression coil spring, which is locked to the base portion of the latch receiver and the spring receiver portion of the latch, and always urges the latch and the latch receiver; and wherein the lever cam that engages with the claw portion of the lever swings around the cam pin in response to the swing of the lever.