expression
cannot do without; indispensable; absolutely necessary
Expresses that something is essential or that one cannot manage without it. Equivalent to 無くてはならない.
See also: 無くてはならない
この仕事には経験がなきゃならない。
Experience is indispensable for this job.
expression
Attaches to the negative stem of a verb (～なきゃならない) to express obligation. Colloquial contraction of ～なくてはならない.
See also: 無くてはならない
明日までにレポートを出さなきゃならない。
I have to submit the report by tomorrow.