A sight includes a main body including a focus lens system and an erecting lens system; a first adjusting member disposed in the main body and configured to move the focus lens system along the optical axis; a second adjusting member disposed in the main body and configured to move the erecting lens system in a first direction which is perpendicular to the optical axis; a focus adjusting module disposed in the main body and configured to drive the first adjusting member so as to move the focus lens system along the optical axis; and a first adjusting module detachably joined to the focus adjusting module and configured to drive the second adjusting member so as to move the erecting lens system in the first direction.