Liquid crystal blue phases (BPs) exist in a very narrow temperature range, usually less than a few Kelvin. In this study, the asymmetrical dimmer with two characters, liquid crystal nature and non-liquid crystal nature, was newly synthesized, and it was added into blue phases. Such the molecule can be expected to stabilize the interface between the ordered region and the defect in BP. By adding the asymmetrical dimmer to BP, the temperature range of BP was successfully extended to ca. 11 K.