A perimeter for measuring a visual field having: a visual field measurer (26,27) that is arranged to measure a visual field of an eye to be examined when the eye to be examined perceives stimuli projected at different positions on a visual field dome: a fixation state monitor that is arranged to monitor a fixation state of the eye to be examined at a time of perimetry; said fixation state monitor having an illuminator with two or more light sources (20,21,22) that light the eye to be examined at a brightness necessary for monitoring the fixation state of the eye to be examined; and a visibility corrector that is arranged to correct defective vision of the eye to be examined; said visibility corrector has a stem being provided with a rotation axis that is located on an outside of an opening of said visual field dome at its center, and a lens holder portion being provided at a top end of the stem so as to be freely adjusted between a set position of a center portion of said opening and a stored position provided at an outer periphery of said opening said perimeter further comprising: a position detector arranged to detect whether said visibility corrector is positioned at said set position or said stored position; and an illumination controller that is arranged to drive respectively two or more light sources (20,21,22) according to the position of said visibility corrector detected by said position detector. a visual field measurer (26,27) that is arranged to measure a visual field of an eye to be examined when the eye to be examined perceives stimuli projected at different positions on a visual field dome: a fixation state monitor that is arranged to monitor a fixation state of the eye to be examined at a time of perimetry; said fixation state monitor having an illuminator with two or more light sources (20,21,22) that light the eye to be examined at a brightness necessary for monitoring the fixation state of the eye to be examined; and a visibility corrector that is arranged to correct defective vision of the eye to be examined; said visibility corrector has a stem being provided with a rotation axis that is located on an outside of an opening of said visual field dome at its center, and a lens holder portion being provided at a top end of the stem so as to be freely adjusted between a set position of a center portion of said opening and a stored position provided at an outer periphery of said opening said fixation state monitor having an illuminator with two or more light sources (20,21,22) that light the eye to be examined at a brightness necessary for monitoring the fixation state of the eye to be examined; and a visibility corrector that is arranged to correct defective vision of the eye to be examined; said visibility corrector has a stem being provided with a rotation axis that is located on an outside of an opening of said visual field dome at its center, and a lens holder portion being provided at a top end of the stem so as to be freely adjusted between a set position of a center portion of said opening and a stored position provided at an outer periphery of said opening said perimeter further comprising: a position detector arranged to detect whether said visibility corrector is positioned at said set position or said stored position; and an illumination controller that is arranged to drive respectively two or more light sources (20,21,22) according to the position of said visibility corrector detected by said position detector. a position detector arranged to detect whether said visibility corrector is positioned at said set position or said stored position; and an illumination controller that is arranged to drive respectively two or more light sources (20,21,22) according to the position of said visibility corrector detected by said position detector.