A semiconductor memory having an error correcting function is provided, which has a device by which the user finds no difficulty in making use of the semiconductor memory and can test it with ease. In the semiconductor memory, a signal indicative of the completion of the preparation for reading/writing is outputted from the memory so that the user, after detecting the output of this signal, performs reading/writing data. To facilitate tests, such as a memory cell test for a redundant bit (check bit), an encoding circuit test and a decoding circuit test, the present invention provides that the arranged tests can be made independently of each other.