Is it possible to give access of particular card to the members and board access only to admin?

[Priya Gupta]

while giving access of the card to any member(guest), that member got access to the full board.

Is it possible to give access to the board to only admins?

[Guilherme Michelotto]

Heyo Priya!

I see that you are a new member here, so welcome to Trello! :)

Hmm, well, it is not possible to break access down to specific cards. You can only have private boards, and anyone with access to a board will be able to see the cards inside of it.

Here's how to invite to invite people to a board and how each type interacts with the board and billing matters.

Have a nice week!

[Theodoro Reato]

Hey Priya, 

Right now, This isn't possible, you would need to create a new board and then move/copy this card to the new board and share the new board with your colleague.

It's only possible to share the board with a user, not the card. This is mainly because Trello was built as a multi-collaborative platform, and permissions like the one you described would go against this core.