Device and method for authenticating user in terminal

A user authentication device of a terminal and a method thereof are provided to conveniently search and select lots of information by using a touch pad and a GUI(Graphic User Interface), and to use various types of passwords, thereby preventing personal information from being leaked without permission. An input part(22) inputs motion information by consecutive contact from a user during at least a certain section. A secret motion storage(1103) stores predetermined secret motion information. A controller(1101) decides whether a user is a legal person, depending on whether the motion information inputted to the input part(22) is identical with the secret motion information stored in the secret motion storage(1103).