The phrase "Son of Man" is a title often applied by Jesus to Himself. It is an allusion to Daniel 7:13-14, which reads:
"I saw in the night visions, and behold, with the clouds of heaven there came one like a son of man, and he came to the Ancient of Days and was presented before him. And to him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve him; his dominion is an everlasting dominion, which shall not pass away, and his kingdom one that shall not be destroyed." The allusion is clearest in Mark 14:61-62:
But he remained silent and made no answer. Again the high priest asked him, "Are you the Christ, the Son of the Blessed?" And Jesus said, "I am, and you will see the Son of Man seated at the right hand of Power, and coming with the clouds of heaven." The phrase to which Jesus alludes so frequently is, in the original text of Daniel 7:13, bar enash, as opposed to the more usual phrase bar 'adam. Bar enash carries the connotation of a foremost heir to a throne. ^^ Therefore, it can be seen as a strong claim to divinity.
In the Gospels
The title "Son of Man" is found approximately 80 times in the four Gospels. In the rest of the NT, it occurs only 4 times in Acts 7:56; Heb 2:6; Rev 1:13, 14:14. ^^
- The Divine Claims of Jesus: The "Son of Man" Title, by James Patrick Holding
- The Son of Man in the Gospels, by Celucien Joseph (blog post)