A polypropylene film satisfying formula I and having a thickness of 1.0 μm to 19 μm, wherein the polypropylene film is a biaxially stretched film, which is preheated to 155°C to 172°C after longitudinal stretching and before transverse stretching, and the polypropylene film being configured such that the formula I is 31.5 ≤ fusion enthalpy/√crystallite size ≤ 33.0, in the formula I, the unit of the fusion enthalpy is J/g, and the unit of the crystallite size is nm, the fusion enthalpy is determined according to the method in the description, and the crystallite size is determined using Scherrer's equation from a full width at half maximum of the reflection peak from plane of α crystal measured by a wide-angle X-ray diffraction method, wherein the polypropylene film comprises a first polypropylene resin and a second polypropylene resin, wherein the first polypropylene resin is comprised as a main component at a content of, relative to 100 wt% of the polypropylene resin, 50 wt% or more, the first polypropylene resin has a number average molecular weight Mn of 30,000 or more and 54,000 or less, the first polypropylene resin has a weight average molecular weight Mw of 250,000 or more and less than 350,000, the ratio of Mw to Mn in the first polypropylene resin is 5.0 or more and 10.0 or less, the first polypropylene resin has a heptane insoluble content of 97.0% or more and 98.5% or less, the first polypropylene resin has a melt flow rate of 4.0 g/10 min or more and 10.0 g/10 min or less, the second polypropylene resin has a number average molecular weight Mn of 40,000 or more and 54,000 or less, the second polypropylene resin has a weight average molecular weight Mw of 350,000 or more and less than 550,000, the ratio of Mw to Mn in the second polypropylene resin is 3.0 or more and 11.0 or less, the second polypropylene resin has a melt flow rate of 1.0 g/10 min or more and less than 4.0 g/10 min, and the second polypropylene resin has a heptane insoluble content of 97.5% or more and 99.5% or less, wherein the number average molecular weight Mn, the weight average molecular weight Mw, the heptane insoluble content and the melt flow rate are determined according to the methods in the description. the polypropylene film being configured such that the formula I is 31.5 ≤ fusion enthalpy/√crystallite size ≤ 33.0, in the formula I, the unit of the fusion enthalpy is J/g, and the unit of the crystallite size is nm, the fusion enthalpy is determined according to the method in the description, and the crystallite size is determined using Scherrer's equation from a full width at half maximum of the reflection peak from plane of α crystal measured by a wide-angle X-ray diffraction method, wherein the polypropylene film comprises a first polypropylene resin and a second polypropylene resin, wherein the first polypropylene resin is comprised as a main component at a content of, relative to 100 wt% of the polypropylene resin, 50 wt% or more, the first polypropylene resin has a number average molecular weight Mn of 30,000 or more and 54,000 or less, the first polypropylene resin has a weight average molecular weight Mw of 250,000 or more and less than 350,000, the ratio of Mw to Mn in the first polypropylene resin is 5.0 or more and 10.0 or less, the first polypropylene resin has a heptane insoluble content of 97.0% or more and 98.5% or less, the first polypropylene resin has a melt flow rate of 4.0 g/10 min or more and 10.0 g/10 min or less, the second polypropylene resin has a number average molecular weight Mn of 40,000 or more and 54,000 or less, the second polypropylene resin has a weight average molecular weight Mw of 350,000 or more and less than 550,000, the ratio of Mw to Mn in the second polypropylene resin is 3.0 or more and 11.0 or less, the second polypropylene resin has a melt flow rate of 1.0 g/10 min or more and less than 4.0 g/10 min, and the second polypropylene resin has a heptane insoluble content of 97.5% or more and 99.5% or less, wherein the number average molecular weight Mn, the weight average molecular weight Mw, the heptane insoluble content and the melt flow rate are determined according to the methods in the description.