Translation guide
To have faith, trust, or confidence in someone or something; to accept the existence or value of something.
Expressing that you trust someone's character, abilities, or reliability.
The most direct and common way to express trusting someone. Used for personal or professional trust.
I believe in him.
She believes in her team.
Can also mean 'believe in' a person, but often implies believing what they say or believing in their existence/qualities. Slightly less common for trust in abilities.
I believe in him. (I believe what he says / I have faith in him)
Expressing belief in the value, truth, or effectiveness of something abstract.
Expressing that you think something exists, such as ghosts, gods, or aliens.
Expressing self-confidence or faith in one's own abilities.
The standard phrase for 'believe in oneself'. Used in motivational contexts.
Believe in yourself.
He couldn't believe in himself.
Literally 'have self-confidence'. A very common alternative, often more natural in some contexts.
Believe in yourself more. (Have more confidence.)
信じる (shinjiru) is broader: it can mean believe in existence, truth, or value. 信頼する (shinrai suru) specifically means trust in reliability, ability, or character. Use 信頼する for trusting people or systems to perform well.
I believe his words.
I trust his ability.
English uses 'believe in', but Japanese uses the particle を with the object of belief. Do not try to translate 'in' literally as に or の中で.