In　the　nondestructive　testing　and　evaluation　area,　magnetic　major　hysteresis　loop　measurement　technology　are　widely　applied　for　ferromagnetic　material　evaluation.　However　the　characterization　ability　of　major　hysteresis　loop　measurement　technology　greatly　varies　as　the　evaluated　target　properties.　To　solve　this　limitation,　magnetic　minor　hysteresis　loops,　which　reflect　the　responses　of　ferromagnetic　material　magnetization　in　a　systematic　way,　is　recommend.　Inspired　by　plenty　of　information　carried　by　the　minor　loops,　the　sensitivity　mapping　technique　was　developed　to　achieve　the　highest　sensitivity　of　minor-loop　parameters　to　the　nondestructively　evaluated　targets.　In　this　study,　for　the　first　time,　the　sensitivity　mapping　technique　is　used　to　measure　the　tensile　force　in　a　steel　strand　and　evaluate　the　effective　case　depth　in　induction-hardened　steel　rods.　The　method　and　procedures　for　the　sensitivity　mapping　technique　are　given　before　experimental　detection.　The　obtained　experimental　results　indicate　that　the　linear　correlation　between　the　induced　voltage　(or　the　magnetic　induction　intensity)　and　the　tensile　force　(or　effective　case　depth)　exists　at　most　of　the　locations　in　the　cluster　of　minor　loops.　The　obtained　sensitivity　maps　can　be　used　to　optimize　the　applied　magnetic　field　(or　excitation　current)　and　the　analyzed　locations　at　the　minor　loops　for　achieving　the　highest　sensitivity.　For　the　purpose　of　tensile　force　measurement,　it　is　suggested　that　the　strand　should　be　firstly　magnetized　to　the　near-saturation　state　and　then　restored　to　the　remanent　state.　In　this　way,　the　highest　sensitivity　is　obtained　as　about　15.26　mV/kN.　As　for　the　induction-hardened　steel　rods,　the　highest　sensitivity　of　magnetic　induction　intensity　to　the　effective　case　depth　occurs　under　low　magnetic　field　conditions　and　the　absolute　value　of　the　highest　sensitivity　is　about　0.1110　T/mm.　This　indicates　that　if　the　highest　sensitivity　is　required　in　the　case　depth　evaluation,　the　induction-hardened　steel　rods　are　only　required　to　be　weakly　magnetized.　The　proposed　sensitivity　mapping　technique　shows　the　good　performance　in　the　high-sensitivity　evaluation　of　tensile　force　and　case　depth　in　ferromagnetic　materials　and　its　application　scope　can　be　extended　to　other　nondestructive　detection　fields.