A collapsible head covering device includes a wide-brimmed hat made of an anti-UV waterproof fabric and having a memory metal wire ring fastened to the border edge of the brim thereof, a cap detachably accommodated in the wide-brimmed hat for capping on the head of a person, and a fastening belt selectively inserted through multiple through holes on the wide-brimmed hat and multiple through holes on the cap to fasten the wide-brimmed hat to the cap in one of multiple different angular positions.