A steam release standing pouch has a structure in which the sealing portion is reliably peeled, and a content sealing standing pouch formed using the pouch. The steam release standing pouch has a first vapor passage portion. The distance between the inner edge of the tip of the vapor passage portion and the center of maximum expansion, which is the center of the portion where expansion is expected to be maximal, is shorter than either the distance between the inner edge of the first upper side portion and the center of maximum expansion or the distance between the inner edge of the first intermediate side portion and the center of maximum expansion.