Is the Bible book 'Acts of the Apostles' in the New Testament or Old Testament?

The New Testament.

Further thought:

The New Testament contains the account of Jesus' life, his fulfillment of prophecy, and his effect on the world. The 'Apostles' were chosen disciples of Christ after he was born on earth(so they were not in the Old Testament). The book of 'Acts' describes the 'deeds or actions' of some of these Apostles in the early days of Christianity