Judas betrayed Jesus for thirty pieces of silver and afterwards hung himself.

Judas, the man who became the traitor, is the supreme enigma of the New Testament because it is so hard to see anyone who was so close to Jesus, who saw many miracles and heard so much of his Master's teachings could ever betray him into the hands of his enemies. 

It is said that Judas was a violent Jewish Nationalist who had followed Jesus in hope that through Him his nationalistic flame and dreams might be realized. 

There is no certain reason as to why Judas betrayed his master; but it is not his betrayal that put Jesus on the cross-it was our sins.