An endoscope comprising: an insertion portion including a flexible portion; an operation portion provided continuously to a base end side of the insertion portion; a coil spring unit including a coil spring provided to extend from the flexible portion to the operation portion; a wire unit provided to extend from the flexible portion to the operation portion and including a wire inserted into the coil spring and fixed to a tip end portion of the coil spring; and a hardness adjuster provided at the operation portion and configured to adjust a hardness of the flexible portion in such a manner that the coil spring is compressed with a base end of the coil spring and a base end of the wire being apart from each other, wherein the hardness adjuster includes a wire holder configured to hold a base end portion of the wire unit protruding toward the base end side beyond a base end portion of the coil spring unit, a coil spring contact portion contacting the base end portion of the coil spring unit, a relative distance changer configured to change a distance in a longitudinal direction of the operation portion between the coil spring contact portion and the wire holder, characterized by a tubular coil spring holder functioning as a first retainer configured to retain a retained portion at first radial position apart from a center axis of the operation portion along the longitudinal direction by a first radius distance, the retained portion being positioned on a tip end side with respect to the base end portion of the coil spring unit, a wire holder functioning as a second retainer configured to retain the base end portion of the wire unit at a second radial position apart from the center axis in a radial direction by a second radius distance longer than the first radius distance, the base end portion of the wire unit being held by the wire holder, and the coil spring contact portion functioning as a third retainer configured to retain the base end portion of the coil spring unit at a third radial position apart from the center axis in a radial direction having a component of the radial direction by a third radius distance longer than the first radius distance and shorter than the second radius distance, the base end portion of the coil spring unit contacting the coil spring contact portion. an insertion portion including a flexible portion; an operation portion provided continuously to a base end side of the insertion portion; a coil spring unit including a coil spring provided to extend from the flexible portion to the operation portion; a wire unit provided to extend from the flexible portion to the operation portion and including a wire inserted into the coil spring and fixed to a tip end portion of the coil spring; and a hardness adjuster provided at the operation portion and configured to adjust a hardness of the flexible portion in such a manner that the coil spring is compressed with a base end of the coil spring and a base end of the wire being apart from each other, wherein the hardness adjuster includes a wire holder configured to hold a base end portion of the wire unit protruding toward the base end side beyond a base end portion of the coil spring unit, a coil spring contact portion contacting the base end portion of the coil spring unit, a relative distance changer configured to change a distance in a longitudinal direction of the operation portion between the coil spring contact portion and the wire holder, characterized by a tubular coil spring holder functioning as a first retainer configured to retain a retained portion at first radial position apart from a center axis of the operation portion along the longitudinal direction by a first radius distance, the retained portion being positioned on a tip end side with respect to the base end portion of the coil spring unit, a wire holder functioning as a second retainer configured to retain the base end portion of the wire unit at a second radial position apart from the center axis in a radial direction by a second radius distance longer than the first radius distance, the base end portion of the wire unit being held by the wire holder, and the coil spring contact portion functioning as a third retainer configured to retain the base end portion of the coil spring unit at a third radial position apart from the center axis in a radial direction having a component of the radial direction by a third radius distance longer than the first radius distance and shorter than the second radius distance, the base end portion of the coil spring unit contacting the coil spring contact portion.