Is National Commission for Backward Classes a constitutional body?

Yes, National Commission for Backward Classes is a constitutional body. It was initially constituted by the Central Govt. by The National Commission for Backward Classes Act, 1993. The present Commission (8th) has been accorded Constitutional Status and constituted through the 102nd Constitutional Amendment Act, whereby Article 338B has been inserted, forming a Commission for the socially and educationally backward classes to be known as NCBC.

Further Reading:

• National Commission for Backward Classes (NCBC)
• Constitutional Bodies