The microwave dielectric properties and crystal structure of Ba(Zn1/3Ta2/3)O3– (Sr,Ba)(Ga1/2Ta1/2)O3ceramics were investigated in the present study. TheQvalue of Ba(Zn1/3Ta2/3)O3was improved by adding 5 mol% Sr(Ga1/2Ta1/2)O3. The maximumQvalue ofQ×f= 162000 GHz was obtained at 0.95Ba(Zn1/3Ta2/3)O3. 0.05Sr(Ga1/2Ta1/2)O3. For this composition, a lattice super structure caused by hexagonal ordering was observed. A further improvement in theQvalue was attained when some Sr was replaced with Ba, and 0.95Ba(Zn1/3Ta2/3)O3· 0.05(Sr0.25Ba0.75)(Ga1/2Ta1/2)O3exhibited a maximumQvalue such thatQ×f= 210000 GHz. Despite the increasedQvalue with the replacement of Sr by Ba, thec/avalue, which indicates the degree of lattice distortion, remained constant near3/2. TheQvalue thus improved without lattice distortion in the system Ba(Zn1/3Ta2/3)O3‐(Sr,Ba)(Ga1/2Ta1/2)O3, whereas the improvement ofQvalue increased with lattice distortion in the solid solution system with Ba(Zn1/3Ta2/3)O3as an end