Strain　engineering　has　been　well　developed　and　widely　used　to　manipulate　properties　of　materials.　For　two-dimensional　materials,　via　nanoindentation　technique　or　depositing　the　materials　onto　flexible　substrates,　one　usually　triggers　tensile　strains.　It　would　be　intriguing　to　develop　strategies　to　generate　strains　via　noncontacting　schemes,　such　as　an　optical　field,　to　eliminate　lattice　damage　and　additional　interactions.　Here　we　theoretically　and　computationally　illustrate　an　optomechanical　approach　(referred　to　as　optostriction),　which　could　induce　intrinsic　strains　in　materials.　Taking　the　well-studied　transition　metal　dichalcogenide　monolayers　as　examples,　we　predict　a　large　in-plane　optostriction　with　strong　anisotropy,　owing　to　their　unique　directional　band　transition　strength.　This　optically　driven　strain　method　can　avoid　direct　and　invasive　mechanical　contacts　with　materials,　which　is　easily　accessible　and　guarantees　the　reversibility　of　materials.　Rather　than　nanoindentation　technique　and　other　similar　methods,　this　optomechanical　strain　can　be　either　tensile　or　compressive.　Owing　to　its　intrinsicality,　compressive　strains　are　robust　without　suffering　Euler＇s　instability.　In-plane　inhomogeneous　strains　can　be　easily　achieved　via　illuminating　a　Gaussian　beam　onto　the　material,　adding　an　interesting　approach　to　realize　and　measure　in-plane　optoflexoelectricity.　Unlike　conventional　electric　field　inducing　strains　in　piezoelectrics,　no　symmetry　constraints　are　required.　©　2020　authors.　Published　by　the　American　Physical　Society.