A quick joint of a front loader, the quick joint includes: a coupling member (30) having a hook shape and pivotally connected to a first pivot point (P1) of a boom post (20) through a first pivot shaft (31); a spring member (32) for applying an elastic force in a direction of releasing the coupling member (30) from a coupling target shaft (14) disposed on a boom post support (10) which is attached to a tractor (1); a lock unit (34) having a part making contact with the coupling member (30), and provided with a lock pin (36) for restraining behavior of the coupling member (30) at a coupling position (A1); and a guide slot (38) having an arc shape and formed in the boom post (20) to define a moving path of the lock pin (36) when the lock unit (34) rotates.