PURPOSE: To embody a caster mounting structure adapted to requirements for recycling and improved with respect to the safety of the caster in use.

CONSTITUTION: When the upper end 31 and lower end 32 of a caster shaft 3 are press fitted respectively in a shaft hole 11 opening to the lower surface of a leg blade 1 and a shaft hole 21 opening to the upper surface of a caster body 2, the fitting strength between the upper end 31 of the caster shaft 3 and the shaft hole 11 of a leg body 1 is set larger than that between the lower end 32 of the caster shaft 3 and the shaft hole 21 of the caster body 2.