Disclosed is a security USB storage medium generation and decryption method. The method comprises outputting information for requesting an input of a user password to be set through the output interface, generating a random key and a disk key based on first user password when the first user password is input from the input interface in response to the input requesting of the first user passwords, generating first encryption and decryption keys by hashing the first user password and the random key, when the random key and the disk key are generated, generating a security volume body part by classifying the storage region into a header and a body part using the first encryption and decryption keys, encrypting first data, storing the data in the header, generating a security volume header, encrypting second data using the disk key and then storing the data in the body part.