The coordinate input pen according to the present invention is a coordinate input pen for specifying a current position of the coordinate input pen by emitting an ultrasonic wave, including: an ultrasonic wave oscillating section for oscillating the ultrasonic wave for specifying coordinates of the current position; an ultrasonic wave emitting outlet for emitting, to an outside, the ultrasonic wave oscillated by the ultrasonic wave oscillating section; and an ultrasonic wave propagation route which has a fixed length and extends from the ultrasonic wave oscillating section to the ultrasonic wave emitting outlet and is used to propagate the ultrasonic wave to the ultrasonic wave emitting outlet. As a result, it is possible to maintain the output level of the ultrasonic wave oscillated by the ultrasonic wave oscillating section constant regardless of how large a stroke pressure applied on the coordinate input pen is.