To provide a leg portion mounting structure capable of easily mounting/demounting a leg portion in spite of pressing the leg portion into a recess of a mounting portion.

The mounting structure S comprises a through-hole 133a provided in the ceiling of the recess 133 of the mounting portion 130 in the vertical direction, a screw hole 211 provided in the front end face of the first leg portion 210 in the vertical direction, a communication hole 233 provided in the ceiling of a thick portion 230 in communication with the screw hole 211, and a screw portion 300 inserted into the through-hole 133a through the upper face side of the mounting portion 130 and threaded to the screw hole 211 of the first leg portion 210 inserted into the recess 133.