According to one or more embodiments of the disclosure, a lens barrel includes an operation member and a knob. The operation member is disposed to be rotatable in a circumferential direction with respect to a lens barrel body. The knob is restricting and fixing rotation of the operation member in the circumferential direction. The lens barrel further includes a knob falling-off prevention member capable of switching between a first state of making the knob detachable from the lens barrel body and a second state of making the knob non-detachable from the lens barrel body.