The present invention relates to an organopolysiloxane elastomer modified with a glycerin derivative and that: does not have, as a hydrophilic group, an oxyalkylene structure in which the mean number of repeating oxyalkylene units is at least 2 has a glycerine derivative group in which the mean number of repeating glycerine units is in the range of 1.0-2.4 and has a three-dimensional cross-linked network structure comprising carbon-silicon bonds in the cross-linking portions. This organopolysiloxane elastomer exhibits, for example, superior compatibility with various oils, emulsification properties, thickening properties, gelling properties, and structural control properties, as well as imparting an excellent sensation (in particular, a thick velvety smoothness) and being pleasant to use, with little stickiness when drying. Furthermore, this invention enable the provision of external preparations and cosmetics exhibiting excellent emulsification stability, not containing compounds comprising polyoxytheylene structures, and in line with the global trend of improving the formulation of end consumer products such as makeup so as to be entirely PEG-free.