Provided is an operation handle mechanism with which a handle can be conveniently operated to move a movable section, thereby ensuring smooth operation and movement at any time regardless of an operation position of the handle. An operation handle section 121 includes a handle lever 67, which is used to operate movement of a support frame section 23 capable of moving up and down, and left and right transmission rods 123a and 123b, which are joined to the handle lever. The transmission rods can only move a predetermined distance in a movement direction thereof relative to the support frame section, and start to move together with the support frame section after going beyond that distance. The left and right transmission rods are connected via rack sections 140a and 140b of the transmission rods and a gear train 134a, 134b, 135a, and 135b meshing with the rack sections in such a way as to enable transmission of part of an operation force coming from the handle lever from one transmission rod to the other and thereby allow the two transmission rods to simultaneously move only the same distance.