Johann Ambrosius Bach (February 22/24, 1645 – February 20/24, 1695) was a German musician, father to Johann Sebastian Bach.

The son of Christoph Bach (1613–1661), Ambrosius was born in Erfurt, Germany as the twin brother of Johann Christoph Bach (1645–1693). Ambrosius was employed as a violinist in Erfurt.

In 1671, he moved his family to Eisenach, Thuringia, where he was employed as a court trumpeter and director of the town musicians. He married his first wife Maria Elisabeth Lämmerhirt on April 1, 1668, and had eight children by her, four of whom became musicians, including Johann Sebastian. She was buried on May 3, 1694. On November 27, 1694 he married Barbara Margaretha, née Keul (she had already been twice widowed). He died in Eisenach less than three months later.