A barrier mechanism includes a barrier blade group (G1) having barrier blades (A1), (B1), (C1) which are rotatably retained by a single spindle (S11); an elastic member (E11) provided to the spindle (S11) substantially coaxially with a rotating center of the barrier blade group (G1), and configured to generate torque for driving the barrier blade (A1) to rotate,' and a frame member formed by a barrier cover (F1) and a barrier (F2) each including an aperture serving as a window for opening an effective optical path of an optical lens, and configured to house the barrier blade group (G1) and the elastic member (E1) between these members. The spindle (S11) includes a flange portion (S11f) configured to separate the barrier blade group (G1) from the elastic member (E11) in a direction of an optical axis.