Buffer managing method and therefore semiconductor storage device

Disclosed in the present invention is an improved buffer operation method of a semiconductor storage device. The method to operate a buffer included in a controller of the semiconductor storage device having a buffer configured to temporarily store user data and map data read from a nonvolatile memory comprises the steps of: comparing the size of the user data to be stored from the nonvolatile memory to the buffer with the size of the user data to be transmitted from the buffer to a host; and adaptively varying a data area of the buffer to store the user data and a map area of the buffer to store the map data according to the comparison result. According to the present invention, the buffer is used for the map area to store map information, thereby improving a map hit ratio. In addition, storage areas of the buffer are dynamically varied such that the buffer having a limited capacity is efficiently used.