To provide a protection element which can retain flux on a fusible conductor at a prescribed position stably, and makes possible to precisely fuse the fusible conductor at the occurrence of an abnormality, and a secondary battery device using the element.

This element has the fusible conductor 13 which is arranged on an insulating base substrate 11 connected to an electric power supply route of an equipment protected and fused by prescribed abnormal electric power, the flux 19 coated on the fusible conductor 13 surface, and an insulating cover member 14 which covers the fusible conductor 13 and is mounted on the base substrate 11. This element has a protruding strip 20 which is formed on the inner face of the insulating cover member 14 opposed to the fusible conductor 13, and in which a stage 20a to retain the flux 19 at a prescribed position by contacting with the flux 19 is formed. The step 20a is formed on the inner face of the insulating cover member 14 in an annular form so as to surround the fusible conductor 13 center.