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

He was the twin brother of Johann Christoph Bach (1645–1693).

In 1671, he moved his family to Eisenach, in present-day Thuringia, where he was employed as a court trumpeter and director of the town musicians.

He married his first wife Maria Elisabeth Lämmerhirt on 1 April 1668, and had eight children by her, four of whom became musicians, including Johann Sebastian Bach, the famous German Baroque composer and musician.

On 27 November 1694 he married Barbara Margaretha, née Keul (she had already been twice widowed).