Photomechanical effects are observed in single crystals of a thiazole-based diarylethene. Crystalline state photochromism has been characterized by absorption microspectroscopy. Clear single crystals turn colored under ultra-violet irradiation. When the energy absorbed by crystals reaches about ten microjoules, they jump. When we prevent crystals from jumping, parallel, equidistant cracks appear due to elastic energy dissipation. These phenomena are associated with a phototransformation ratio of only a few percent.