An endoscope with adjustable viewing angle, in which the viewing angle can pivot around a pivot axis, includes a fixed reflecting surface for reflecting illuminating light from a direction parallel to the longitudinal axis of the endoscope to a direction parallel to the pivot axis of the viewing angle and a pivotable reflecting surface for reflecting illuminating light from a direction parallel to the pivot axis of the viewing angle to the viewing angle for illuminating an object observed by the endoscope, such that at least either the fixed reflecting surface or the pivotable reflecting surface is curved.