To high-precisely regulate the oscillation angle of an inner cylinder by a method wherein a recessed spherical seat is formed on the central line of the inner peripheral part of a scope body and a protrusion spherical part on the central line of the outer peripheral part of an inner cylinder, and the recessed and protrusion spherical parts are fitted in each other.

A spherical recessed part 11c is formed in the inner peripheral surface of an intermediate part between a large hole 11b of a body cylinder 11 and the object side. A spherical recessed part 35b having the same diameter as that of the spherical recessed part 11c is formed in the inner peripheral surface of the end part on the object side of a cylinder body 35 insertable in the large hole 11b, and a spherical seat 40 consists of the two parts. Meanwhile, a spherical part 50 having approximately the same diameter as those of the spherical recessed parts 11b and 35c is formed on the outer peripheral surface on the eyepiece side of the inner cylinder 20, and rotatably fitted in the spherical seat 40 and the inner cylinder 20 is oscillatorily displaceable in an omnidirectional way. Since the body cylinder 11 and the inner cylinder 20 of a scope body 10 are spherically fitted in each other, when regulation screws 31 and 32 are moved forward and backward, the inner cylinder 20 is oscillated by an amount equivalent to the forward and backward movement. This constitution always accurately regulates an oscillation amount of the inner cylinder 20.