Abstract: This polypropylene film has a polypropylene-based resin as a main component, and is configured such that the value (strength X) obtained by multiplying the film thickness by the F5 value in a direction perpendicular to the principal orientation axis is 400 N/m or more and 2000 N/m or less. As measured by thermomechanical analysis (TMA), when: the thermal shrinkage (%) at 100° C. in a direction perpendicular to the principal orientation axis is SMD, 100° C.; the thermal shrinkage at 130° C. in a direction perpendicular to the principal orientation axis is SMD, 130° C.; the thermal shrinkage at 100° C. in the principal orientation axis direction is STD, 100° C.; and the thermal shrinkage at 130° C. in the principal orientation axis direction is STD, 130° C., the propropylene film satisfies |SMD, 100° C.?SMD, 130° C.|?2.00 and |STD, 100° C.?STD, 130° C.|?2.50.

Abstract: An oxide magnetic material provided by the present invention contains, as main components, 55 to 59 mol % of Fe.sub.2 O.sub.3 ; 35 to 42 mol % of MnO; and 6 mol % or less of ZnO, and further contains, as sub-components, 0.05 to 0.3 wt % of CaO; and 0.005 to 0.05 wt % of SiO.sub.2. The other oxide magnetic material provided by the present invention contains, as main components, 61 to 67 mol % of Fe.sub.2 O.sub.3 ; 3 to 36 mol % of MnO; and 30 mol % or less of ZnO, and further contains, as sub-components, 0.05 to 0.5 wt % of CaO; and 0.005 to 0.2 wt % of SiO.sub.2. Such materials can further contain one or more kinds of oxides selected from the group consisting of ZrO.sub.2, HfO.sub.2, Ta.sub.2 O.sub.5, Cr.sub.2 O.sub.3, MoO.sub.3, WO.sub.3, Al.sub.2 O.sub.3, Ga.sub.2 O.sub.3, In.sub.2 O.sub.3, GeO.sub.2, SnO.sub.2, Sb.sub.2 O.sub.3 and Bi.sub.2 O.sub.3.