An introducer device (3) is for use in Nuss procedure to guide a steel bar (4) in retrieving an insertion route which passes through and between a patients sternum (903) and heart (904). The introducer device (3) includes an elongated introducer body (31) and an ultrasonic probe (312). The introducer body (31) extends in a lengthwise direction to terminate at a leading tip end (311) for coupling the concave steel bar (4) to retrieve the insertion route, and a grip end (312) opposite to the leading tip (311), and has a curve segment (313) configured to establish the insertion route when the leading tip end (311) is led to pass through and between the sternum (903) and the heart (904) . The curve segment (313) has a concave sternum-side surface (314) and a convex heart-side surface (315). The ultrasonic probe (32) is coupled to the leading tip end (311) to transmit ultrasonic waves towards the heart (904) and to receive reflected ultrasonic waves traveling from the heart (904) when passing through and between the sternum (903) and the heart (904).
