This engaging member includes a male part and a female part each of which is capable of engaging with each other, in which each of the male part and the female part has a welded part to a main body of a bag and a part other than the welded part, at least the welded part is formed by a resin composition including (A) a polypropylene type resin having a maximum melting peak temperature measured by a differential calorimeter of not more than 145° C., and a melt flow rate ranging from 0.5 g/10 min. to 20 g/10 min., and (B) a polybutene type resin having a maximum melting peak temperature measured by a differential calorimeter of not more than 130° C., and a melt flow rate ranging from 0.1 g/10 min. to 20 g/10 min.