His book is oriented towards children, but here and there are words that he has never seen before. He doesn't know whether it is just him, or if they are just simply difficult words, but he finds them not worth the effort to look up in a dictionary, so he just keeps on reading.
彼の本は子供向けなんだけど、ちょくちょく見たことのない単語が飛び出す。それが彼独自の言葉なのか単に難しい単語なのかわからないんだけど、面倒なので辞書も引かず読み進めている。