The Bible doesn't specifically speak of "guardian angels" as it does other types of angels (such, as, cherubim etc.) but Jesus, when speaking of children, said, "See that you do not look down on one of these little ones. For I tell you that their angels in heaven always see the face of My Father in heaven."

(Matthew 18:10)

From this verse, and from other verses in the Bible (such, as, Psalm 91:11-12 and Hebrews 1:14) there is the belief that there are angels assigned to protect us. The Bible doesn't speak of a specific group of angels known as "guardian angels" however.