Optical adhesive sheet containing a base polymer having a first glass transition temperature and an oligomer having a second glass transition temperature higher than the first glass transition temperature

This invention provides an optical adhesive sheet suitable for use in flexible devices. An adhesive sheet 10 (optical adhesive sheet) of this invention contains a base polymer having a first glass transition temperature and an oligomer having a second glass transition temperature higher than the first glass transition temperature, and has an adhesive surface 11 and an adhesive surface 12. A component analysis in the thickness direction H from the adhesive surface 12 side to the adhesive surface 11 side is performed by TOF-SIMS method for the adhesive sheet 10 in a state in which a substrate S is adhered to the adhesive surface 11. A detection maximum peak of an ion strength of a first fragment derived from the oligomer is detected between a detection start time of a second fragment derived from the substrate and a detection end time of a third fragment derived from the base polymer after the detection start time. A ratio of the ion strength of the detection maximum peak to the average value of the ion strengt