A first rail 41 supports a first rolling body 45 so as to allow the first rolling body 45 to be rollable in a first direction parallel to an optical axis of a first focus lens. A second rail 42 supports a second rolling body 46 so as to allow the second rolling body 46 to be rollable in the first direction. The biasing mechanism 47 supports the first rolling body 45 so as to allow the first rolling body 45 to be movable in the first direction, and biases the first rolling body 45 toward the first rail 41. A third rail 43 is provided in parallel with the second rail 42. The third rail 43 supports a second rolling body 46 so as to allow the second rolling body 46 to be movable in the first direction.