A cavitation surface processing nozzle includes: a nozzle tip including a first plane from which liquid is ejected and perpendicular to an ejection axis; a second plane perpendicular to the ejection axis and another side plane of the first plane; and a nozzle hole including a discharge groove located on the first plane and having a semi-cylindrical shape extending in a first direction perpendicular to the ejection axis, an ejection hole extending along the ejection axis to be connected to the discharge groove and having a right elliptic cylindrical shape having an elliptic cross section with a long diameter extending in the first direction, and an introduction portion having a right conical surface centered on the ejection axis and connected to the ejection hole.

A cavitation surface processing nozzle includes: a nozzle tip including a first plane from which liquid is ejected and perpendicular to an ejection axis; a second plane perpendicular to the ejection axis and another side plane of the first plane; and a nozzle hole including a discharge groove located on the first plane and having a semi-cylindrical shape extending in a first direction perpendicular to the ejection axis, an ejection hole extending along the ejection axis to be connected to the discharge groove and having a right elliptic cylindrical shape having an elliptic cross section with a long diameter extending in the first direction, and an introduction portion having a right conical surface centered on the ejection axis and connected to the ejection hole.