The base material for pressure-sensitive adhesive tape or sheet is constituted of a polyolefin based resin as the major component and is obtained by rolling by means of a calender having a measure capable of individually changing the rotational speed of each calender roll. Examples of the measure capable of individually changing the rotational speed of each calender roll include a measure provided with motors capable of individually driving their respective calender rolls and a measure provided with speed regulators capable of individually regulating their respective calender rolls. It may be employed that the number of calender rolls is four and that the roll arrangement is in the reverse L shape. It is preferable that the base material for pressure-sensitive adhesive tape or sheet contains an inorganic compound together with the polyolefin based resin.