have to ~ must ~ どちらも ~しなければならない という意味ですね。
では、その違いは?
たとえば
☆I have to study harder.
★I must study harder.
の違いは?
I have to study harder. は
(誰かに言われたから とか テストが近いから) もっと勉強しなくちゃ
I must study harder. は
(必ず成績を上げたいという思いから とか 自分に言い聞かせて) もっと勉強しなくちゃ
have to は自分以外の理由(ルールや決まり等)で
must は自分の気持ちや意志で
同じ意味に見えても、気持ちの向きが違うんですね
では最後にもうひとつ例文を
☆I have to go home now.
★I must go home now.
I have to go home now. は
(門限がある・親に言われた・終電がある)ので もう帰らなくちゃ
I must go home now. は
(もう帰るべきだと自分で判断した)ので もう帰らなくちゃ
have to と must は「理由」に注目すると違いが分かりやすくなりますね
Both have to and must mean “have to / must do something.”
So, what is the difference?
For example:
☆ I have to study harder.
★ I must study harder.
What is the difference between them?
I have to study harder.
→ I have to study harder because someone told me to, or because a test is coming.
I must study harder.
→ I must study harder because I really want to improve my grades, or because I am telling myself to do so.
In short,
have to is used when the reason comes from outside yourself (rules, situations, or other people),
while must is used when the reason comes from your own feelings or strong intention.
They may look the same in meaning, but the direction of the feeling is different.
Now, let’s look at one more example.
☆ I have to go home now.
★ I must go home now.
I have to go home now.
→ I have to go home now because there is a curfew, my parents told me to, or I need to catch the last train.
I must go home now.
→ I must go home now because I think it’s time to go home and decide so myself.
When you focus on the reason,
the difference between have to and must becomes much clearer.


