A method of a mobile device including a display unit having a panel to display a screen to set the mobile device to a security mode requiring a security check process to enter a password for a user to access a normal mode of the mobile device, a functional unit to photograph an object and sense a motion of the mobile device, and a control unit configured to not apply the security check process for the normal mode of the mobile device according to the photographed object and the sensed motion of the functional unit.