Hello Choton,
Though salary slips confirm your employment and your salary details with your current employer,
If you are able to give your appointment letter or confirmation letter it always is safer.
Secondly, the salary slip might be taken into consideration in the case if you do not have appointment letters etc, only if the salary slip has details as such -
1) Employer's name (Company's name, address, contact details)
2) Your full name & designation
3) Your date of joining
4) Month for which the salary is given.
5) Particulars of salary with proper deductions and stating reasons for same.
6) Signature of the authority.
However will suggest to wait for senior's advises.