1. A perimeter for measuring a visual field of a subject eye by conducting predetermined perimetry operations for two or more measurement points of the subject eye, comprising: a memory that stores perimetry results; a perimetry result indicator that composes the perimetry result as a map image that corresponds to a fundus and indicates it on a display; a structure examination image indicator that obtains a structure examination image of the subject eye on which the perimetry is conducted and indicates the obtained image on the display; a composite image preparing means that superimposes the map image on the displayed structure examination image and indicates the superimposed on the display as a composite image; an input portion that is operated by an operator watching a composite image and designate concerned areas to be monitored regarding change-with-time by the unit of the area; a concerned area setter that sets a concerned area on the composite image by designating with the input portion; and an evaluation value computer that computes an evaluation value of the perimetry regarding the concerned area based upon the perimetry result and outputs it, wherein the memory stores the perimeter results of the subject eye in different times, and the evaluation value computer respectively computes and outputs the evaluation values of the perimetry at two or more points of time that are respectively different.