We have revealed that SrCaMgSi2O7:Eu phosphors emit blue-greenish light under the application of a mechanical stress, called mechanoluminescence (ML). The ML showed a similar spectrum to photoluminescence (PL), which indicated that ML is emitted from the same center of Eu2+ ions as PL. Such a blue-greenish light of ML emission can be seen by the naked eye when pressing the sample. In addition, the ML intensity of SrCaMgSi2O7:Eu proportionally increased with the increase of mechanical load. (c) 2007 The Electrochemical Society.