1. A stimulating task presentation device in a living body optical measurement device comprising: a stimulation presenting unit that presents a stimulation to an examinee; a brain function measuring device that measures a brain function of the examinee in parallel to the presentation of the stimulation; and a stimulation presentation controller that controls the stimulation presented by the stimulation presenting unit, wherein the stimulation presentation controller comprises: setting means that sets a resting task and a stimulating task to be presented to the examinee; detecting means that detects a response of the examinee to the resting task and the stimulating task; and task presentation control means that determines the degree of stability on the basis of the detection result when the resting task is presented, and controls the presentation of the resting task or the stimulating task on the basis of the degree of stability.