A pressure-sensitive adhesive composition of the present invention can suitably contain an ether group-containing compound. The pressure-sensitive adhesive composition may become a pressure-sensitive adhesive composition further excellent in antistatic property by containing the above-mentioned ether group-containing compound. Although it is not clear that the reason why the antistatic property is improved by the use of an ether group-containing compound, through using together an ether group-containing compound improves the wettability to nonpolar materials such as fluoro resin and the transfer of an ionic liquid to an adherend can be carried out effectively.
 
  On the other hand, a pressure-sensitive adhesive layer of the present invention is characterized in that the aforementioned pressure-sensitive adhesive composition is crosslinked. By performing crosslinking by appropriately regulating a constitutional unit and a constitutional ratio of a (meth) acryl-based polymer, selection of a crosslinking agent, and an addition ratio, a surface protecting film more excellent in heat resistance and weather resistance can be obtained.
 
  In addition, a pressure-sensitive adhesive sheet is characterized in that the sheet has a pressure-sensitive adhesive layer, which is formed by crosslinking a pressure-sensitive adhesive composition as defined above on one side or both sides of a support. According to the pressure-sensitive adhesive sheet of the present invention, since the pressure-sensitive adhesive composition of the present invention exerting the aforementioned action and effect is used, electrification of an adherend (subject to be protected) which has not electrification-prevented can be prevented upon peeling, and a pressure-sensitive adhesive sheet which can reduce staining property on an adherend (subject to be protected), and excellent adhesion reliance can be obtained.
 
  A pressure-sensitive adhesive sheet of the present invention includes those in the forms of a sheet, a tape, and a film state such as a pressure-sensitive adhesive tape, a double-sided pressure-sensitive adhesive tape, and a pressure-sensitive adhesive film, as well as a pressure-sensitive adhesive sheet.
 
  Furthermore, when the pressure-sensitive adhesive composition of the present invention is applied to a surface protecting film, it is preferable that a plastic substrate used in a protecting film is antistatic-treated. By subjecting the plastic film to electrification preventing treatment, more excellent antistatic property is obtained.