The present invention relates to an apparatus and method for monitoring the water level within a pipe. The present specification discloses a method for monitoring the water level in a pipe, comprising the steps of: transmitting ultrasonic waves generated at a plurality of ultrasonic transducers, which are spaced apart from each other in the outside of the pipe, to the inside of the pipe via a solid contact medium; checking whether echoes corresponding to respective ultrasonic waves are present; and determining the water level on the basis of the presence of the echoes corresponding to the respective ultrasonic waves. The present invention can simply and conveniently install water level monitoring equipment within a pipe on a long term basis using a nondestructive method.