Liquid crystal composition and liquid crystal display device

A liquid crystal composition that has a positive dielectric anisotropy and contains at least one compound selected from compounds represented by formula (1) as a first component, and at least one compound selected from compounds represented by formula (2) as a second component, wherein a proportion of the first component is in the range of 3% by weight to 40% by weight based on the weight of the liquid crystal composition, and a proportion of the second component is in the range of 10% by weight to 70% by weight based on the weight of the liquid crystal composition:

• wherein, in formula (1) and formula (2), R1 is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons;
• R2 is propyl;
• R3 is vinyl;
• rings A and B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;
• Z1, Z2 and Z3 are independently a single bond, ethylene, vinylene, acetylene, methyleneoxy, carbonyloxy or difluoromethyleneoxy, and at least one of Z1, Z2 and Z3 is difluoromethyleneoxy;
• X1 and X2 are independently hydrogen or fluorine;
• Y1 is fluorine, chlorine, alkyl having 1 to 12 carbons in which at least one piece of hydrogen is replaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in which at least one piece of hydrogen is replaced by fluorine or chlorine, or alkenyloxy having 2 to 12 carbons in which at least one piece of hydrogen is replaced by fluorine or chlorine;
• and a and b are independently 0, 1 or 2.