kanarazushimo かならず 必ずしも

Adverb (used with a negative) meaning: (not) always, (not) necessarily, (not) all

It can be shortened to kanarazu 必ず, or replaced by itsumo いつも.

1. Used with negative
お金は必ずしも必要ではない。
O-kane wa kanarazushimo hitsuyou dewa nai.
Money is not always necessary.

2. Used with dictionary form of verb/adjective + to wa kagiranai
それが必ずしもうまく行くとは限らない。
Sore ga kanarazushimo umaku iku to wa kagiranai.
It will not necessarily go well.
先生が必ずしも正しいとは限りません。
Sensei ga kanarazushimo tadashii to wa kagirimasen.
The teacher is not always right.