A wearable cognitive function evaluation assisting device includes a wearable garment, a near infrared (NIR) light source, an image capturing unit, a storage unit, a projection unit, a sound-recording unit, a processing unit, a transceiver, a control unit, and a power supply unit. The image capturing unit can be selectively extracted from the wearable garment for capturing a continuous image of an oxygenated heme (HbO2) where the NIR light source is irradiated. The projection unit can be selectively extracted from the wearable garment for projecting one of the cognitive environment images stored in the storage unit. The processing unit converts the question and answer recorded by sound-recording unit into a question and answer audio signal. The transceiver receives the continuous image of HbO2 and the question and answer audio signal and then transmits them out.
