An apparatus, which noninvasively measures glucose in a subject optically, comprising: a probe (11; 101, 102; 201); a light source (6, 210) and a light detector (7; 216) both of which are connected to the probe (11; 101,102; 201); an elevating mechanism (20, 116) which moves the probe, and a control unit (21, 117) which: controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a first displacement, the movement for the first displacement causing the probe (11; 101,102; 201) to contact with a skin part of the subject under a first pressure; controls the elevating mechanism (20, 116) to maintain the first displacement for a predetermined period of time without performing the noninvasive measurement; controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a second displacement which is smaller than the first displacement, the movement for the second displacement causing the probe (11; 101,102; 201) to contact with the skin part under a second pressure which is lower than the first pressure; and controls the light source and the light detector to perform the noninvasive measurement when the probe is at the second displacement; characterized in that the control unit (21, 117) controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) to separate from the subject between the first and the second displacement, the movement for the separation relieving the contact between the probe (11; 101,102; 201) and the skin part. a probe (11; 101, 102; 201); a light source (6, 210) and a light detector (7; 216) both of which are connected to the probe (11; 101,102; 201); an elevating mechanism (20, 116) which moves the probe, and a control unit (21, 117) which: controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a first displacement, the movement for the first displacement causing the probe (11; 101,102; 201) to contact with a skin part of the subject under a first pressure; controls the elevating mechanism (20, 116) to maintain the first displacement for a predetermined period of time without performing the noninvasive measurement; controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a second displacement which is smaller than the first displacement, the movement for the second displacement causing the probe (11; 101,102; 201) to contact with the skin part under a second pressure which is lower than the first pressure; and controls the light source and the light detector to perform the noninvasive measurement when the probe is at the second displacement; characterized in that the control unit (21, 117) controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) to separate from the subject between the first and the second displacement, the movement for the separation relieving the contact between the probe (11; 101,102; 201) and the skin part. controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a first displacement, the movement for the first displacement causing the probe (11; 101,102; 201) to contact with a skin part of the subject under a first pressure; controls the elevating mechanism (20, 116) to maintain the first displacement for a predetermined period of time without performing the noninvasive measurement; controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) toward the subject for a second displacement which is smaller than the first displacement, the movement for the second displacement causing the probe (11; 101,102; 201) to contact with the skin part under a second pressure which is lower than the first pressure; and controls the light source and the light detector to perform the noninvasive measurement when the probe is at the second displacement; characterized in that the control unit (21, 117) controls the elevating mechanism (20, 116) to move the probe (11; 101,102; 201) to separate from the subject between the first and the second displacement, the movement for the separation relieving the contact between the probe (11; 101,102; 201) and the skin part.