To prevent filling materials such as inner polished rice from overflowing at one sweep in such a way that only a portion of a seal opening is opened, even if tearing up for a full length of the seal opening of a tear part, when transferring the polished rice from a polyethylene bag mainly filling the polished rice to other container, concerning a polyethylene packaging box with the portion of the seal opening openable by linearly tearing the seal opening.

A polyethylene packaging box is configured such that a portion of a seal opening can be opened by linearly tearing thereof. A bag (1) is formed by a polyethylene film having properties that are linearly tearable in one direction. Stepped linear heat seals (5₁).(5₂) are provided in two steps of top and bottom for a full length of a width (W) of an upper seal opening (2). Also, a heat seal part of the top and bottom steps is connected by a narrow vertical line-shaped heat seal part (5₃) at a predetermined height (h). A notch part for linearly tearing up in one direction is provided in a longitudinal side between the heat seal part of two steps of top and bottom.