What it means
ねばならない expresses a strong obligation: someone must do something or has to do it. It is formed from the negative stem of a verb, followed by ねばならない, and is more formal and written than なければならない. Although its surface form contains a negative element, the overall meaning is positive obligation. The polite counterpart is ねばなりません.
Usage note
ねばならない is formal and can sound literary or official in everyday conversation. In ordinary speech, なければならない or なくてはいけない is more common. Do not confuse this construction with a sentence meaning that something must not be done.
How to use it
Verb negative stemねばなりません
研究者はデータを確認せねばなりません。
The researcher must check the data.
Verb negative stemねばならない
研究者はデータを確認せねばならない。
The researcher must check the data.