To provide an apparatus for automatically detecting the shoulder joint position of a poultry carcass.

The apparatus includes an arm member 2 which has a downward-protrusion formed in a tip and is placed on the upper side of a conveyer 100 running while maintaining the upper half part 300 of the poultry carcass from which a cephalic part is extirpated and viscera is eliminated; a spring 5 for downwardly biasing an arm member top by oscillating the arm member 2 in the circumference of a horizontal axis line; a stopper 2f' for specifying the lowest position of the arm member top; a first detector for detecting the vertical distance of the arm member top from the conveyer 100; and a second detector for detecting the horizontal distance of the arm member from the conveyer 100. The detection apparatus presses an arm-member top vicinity section biased downwardly by the spring 5 to the shoulder joint neighborhood of the poultry carcass from above, transfers the arm member top vicinity section to a shoulder joint depression part, and detects the vertical distance and horizontal distance of the arm member top from the conveyer 100 when the downward protrusion of the arm member top makes contact with and rides on a shoulder joint depression part of the poultry carcass.