Here we will see Section 5 of The Hindu Marriage Act.
Conditions for a Hindu Marriage – A marriage may be solemnized between any two Hindus, if the following conditions are fulfilled, namely :
(i) neither party has a spouse living at the time of the marriage;
1[(ii) at the time of the marriage, neither party
(a) is incapable of giving a valid consent to it in consequence of unsoundness of mind; or
(b) though capable of giving a valid consent, has been suffering from mental disorder of such a kind or to such an extent as to be unfit for marriage and the procreation of children; or
(c) has been subject to recurrent attacks of insanity 2 ***];
(iii) the bridegroom has completed the age of 3[twenty-one years] and the bride, the age of 4[eighteen years] at the time of the marriage;
(iv) the parties are not within the degrees of prohibited relationship unless the custom or usage governing each of them permits of a marriage between the two;
(v) the parties are not sapindas of each other, unless the custom or usage governing each of them permits of a marriage between the two;
4 * * * * *
1. Subs. by Act 68 of 1976, s. 2, for clause (ii) (w.e.f. 27-5-1976).
2. The words or epilepsy omitted by Act 39 of 1999, s. 2 (w.e.f. 29-12-1999).
3. Subs. by Act 2 of 1978, s. 6 and Schedule for elighteen years (w.e.f. 1-10-1978).
4. Subs. by s. 6 and Schedule, ibid., for fifteen years (w.e.f. 1-10-1978).
5. Clause (vi) omitted by s. 6 and Schedule, ibid. (w.e.f. 1-10-1978).