PURPOSE: To properly execute sewing even in the case cloth is thick and protruded size of a shank of a ring button is small, in the button sewing machine for sewing the ring button to the cloth.

CONSTITUTION: A button base 3 is provided so as to be adjacent to a cloth base 4. The button base 3 is supported so as to freely retractable between a stand-by position being adjacent to the cloth base 4 and an operating position for separating and advancing from the cloth base 4. In the advance position of the button base 3, a chuck 5 for holding a ring button B is provided. A cloth part which hangs down between a button main body 22 and the button base 3 is pressed against the button main body 22 by the button base 3 and held and pressed, and cloth thickness in the part being adjacent to a needle location point is minimized.