Cal. Mil. & Vet. Code § 162

The Adjutant General shall be appointed by the Governor with the advice and consent of the Senate, and shall hold office at the pleasure of the Governor, or until his successor is appointed and has qualified. No person is eligible for appointment as Adjutant General unless he had not less than a total of ten (10) years of commissioned service in the National Guard of the United States, of which at least four (4) years shall be service as a field grade officer in the California National Guard within the preceding 10-year period prior to the date of appointment and of which at least four (4) years shall have been in command of army or air troops at the battalion or equivalent or higher command level or four (4) years as a staff officer at brigade or equivalent or higher staff level.