A polypropylene based sealant film for retort packaging includes a film made of a resin composition that contains 70 to 85 wt % of a propylene/ethylene block copolymer (a) and 15 to 30 wt % of a low-density polyethylene based polymer (b), wherein, as for the propylene/ethylene block copolymer (a), a proportion of a 20° C. xylene insoluble portion is 75 to 85 wt % relative to 100 wt % of (a), a limiting viscosity ([η]H) of the insoluble portion is 1.7 to 2.0 dl/g, and a limiting viscosity ([η]EP) of a soluble portion is 3.0 to 3.4 dl/g, and the low-density polyethylene based polymer (b) has a density of 0.900 to 0.930 g/cm3 and a melt flow rate of 1 to 10 g/10 minutes.