PROBLEM TO BE SOLVED: To provide a pressure plasma treatment device which can suppress occurrence of abnormal discharge in application of a high voltage, which makes a treatment effect great and which makes a stable discharge area wide, a medical instrument, and an atmospheric pressure plasma treatment method.SOLUTION: An atmospheric pressure plasma generating device includes: a hollow insulator 1 that is elongated in an axial direction a single electrode 2 that is arranged within a space 5 surrounded by inner wall surfaces 1a of the insulator 1 and a power source 4 for applying an AC voltage to the single electrode 2.
