Is annexure ii (salary details) in form 24q(tds) mandatory?

yes you have to filled all this information because on that basis employer give form no. 16

Actually, I am a director of the company. 

yes fill all the information

Annexure I has to be filed and submitted for all four quarters of a financial year. Annexure II is not required to be submitted in the first three quarters. Annexure II has to be furnished submitted only for the fourth quarter of every financial year with the salary details of all employees for the entire financial year.
The Form 24Q has two annexures–Annexure I and Annexure II. Annexure I contains details about the deductor, challans and deductees. There are no salary details in Annexure I. Annexure II contains the salary details.