To provide a diaphragm apparatus that improves qualities of blur and ghost shape.

The diaphragm apparatus includes a rotary arm 5 and first to fourth diaphragm blades. The rotary arm 5 rotates about a rotation shaft CL1. The first diaphragm blade 1 includes a first pair of sides 1a and 1b which are connected to the rotary arm 5 and formed to define a V-shaped apex of an obtuse angle. The second diaphragm blade 2 includes a second pair of sides 2a and 2b which are connected to the rotary arm and formed to define a V-shaped apex of an obtuse angle. The third diaphragm blade 3 includes a third pair of sides 3a and 3b which are connected to the rotary arm and formed to define a V-shaped apex of an acute angle. The fourth diaphragm blade 4 includes a fourth pair of sides 4a and 4b which are connected to the rotary arm and formed to define a V-shaped apex of an acute angle. The area of an aperture defined by the first to fourth pairs of sides 1a, 1b, 2a, 2b, 3a, 3b, 4a and 4b surrounding the same varies in accordance with the rotation of the rotary arm.

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