1. An imaging device, comprising: an image sensor which outputs a signal indicating a series of images obtained by sequential shooting; a tracking processing portion which, based on the output signal of the image sensor, detects a position of a tracking target on the series of images and thereby tracks the tracking target on the series of images; a tracking evaluation portion which, based on the output signal of the image sensor, evaluates a degree of reliability, or of ease, of tracking by the tracking processing portion, and classifies the degree into one of a plurality of levels; a display portion which displays the series of images; and a display control portion which makes the display portion display an evaluation result by the tracking evaluation portion, wherein the display control portion makes the display portion display a tracking target icon corresponding to the tracking target and a level icon indicating the degree which has been evaluated, and further wherein, the tracking processing portion performs tracking of the tracking target based on color information of the tracking target, the color information being specified by the output signal of the image sensor, and the tracking target icon has a color corresponding to the color information.