To Cross verify the prepared testcases and test scripts 
with user requirements.

To monitor the changes , enhance occured during the 
development of the project.

Tracebility matrix is prepared in order to cross check the 
testcases designed against each requirement, hence giving 
an opportunity to verify that all the requirements are 
covered in testing the application.

TM is also useful to derive testcases execution startegy 
for testing.