To provide a leg rest mechanism having a small number of parts.

The leg rest mechanism includes a support frame 13, a seat frame 41 the back of which is turnably provided on the support frame 13 and the front of which is liftable, a leg rest 31 disposed in the front of the seat frame 41, a link 27 up/down turnably provided on the front of the support frame 13 and an actuator (drive source) 35 for driving the leg rest 31 between a storing position and a using position. The second arm 27a of the link 27 engages with the front of the seat frame 41. The leg rest 31 is provided on the first arm 27a. The second arm 27b raises the front of the seat frame 41 by a turn of the link 27 in a direction that the leg rest 31 transfers to the using position.