child's face; childlike face
Literal noun use for the face of a child or an innocent, childlike face; in everyday Japanese, 子どもの顔 is more direct when simply saying 'a child's face.'
This painter is good at depicting innocent children's faces.
noun, noun which may take the genitive case particle 'no'
baby face; childlike face; boyish face
Most common for an older child or adult whose face looks younger than their actual age. Often used predicatively as 童顔だ or attributively as 童顔の.
He has a baby face, but he is already in his thirties.
He is popular as a baby-faced actor.
Because he has a baby face, he's often taken for younger than he really is.
Having a baby face can work to your advantage sometimes, and against you other times.
Despite her baby face, she speaks in a calm and composed manner.