In this thesis, I study the finite N corrections to the superconformal index in AdS/CFT correspondence. AdS/CFT is a conjecture of a duality between 4d conformal field theories and type IIB superstring theory on AdS spacetime . The superconformal index has information of the operator spectrum of the theory and should be the same on both sides of the correspondence. In the large N limit, the agreement was already confirmed but in the finite N region, no methods to calculate the index on the AdS side were known. In this thesis, I propose a calculation method of the index on the AdS side in the finite N region. And I apply this method to S-fold theories to find the index of the S-fold theories through AdS/CFT.

Finite N correction, superconformal index, AdS/CFT