A method for entering password and a portable electronic device using the same, a method for unlocking the portable electronic device and a data authenticating method are provided, wherein the portable electronic device includes a touch screen. The method includes displaying an interface for entering a somatosensory password, measuring and recording at least one angle variation of the portable electronic device on at least one dimension, and generating a somatosensory signal data set according to the at least one angle variation of the portable electronic device on the at least one dimension. The method further includes generating a user password data according to the somatosensory signal data set, encrypting the user password data according to an encryption algorithm to generate an encrypted user password data, and transmitting the encrypted user password data to an authentication unit.