A periodontal pocket depth measuring device comprising:a main body；a probe tabular in shape extending from a side of the main body and the probe is mounted within the main body, the probe comprises a concave structure which is located at the front end of the protruding direction and in the middle of the tabular width direction；a lip extending from the side of the main body along the same protruding direction as the probe, wherein the lip can freely move in parallel to the protruding direction, the lip is slidably mounted into the main body and is located close to the probe； anda measuring portion measuring the depth by measuring the movement in a direction opposite to the lip protruding direction.
