Pursuant to California Penal Code section 25610, a United States citizen over 18 years of age who is not prohibited from firearmpossession, and who resides or is temporarily in California, may transport by motor vehicle any handgun provided it is unloaded and locked in the vehicle's trunk or in a locked container.
Generally you may not carry a concealed firearm on your person in public unless you have a valid Carry Concealed Weapon (CCW) license. CCW licenses are issued only by a California county sheriff to residents of the county, or the chief of police to residents of the city. California law does not honor or recognize CCW licenses issued outside this state.
(Pen. Code, §§ 25400-25700, 26150-26225.)