To investigate the total emission characteristics of single‐crystal LaB6cathodes, the dependence of brightness and emittance (the product of crossover size and beam divergence) on cathode tip curvature were measured. The smaller the radius of the tip curvature and the lower the tip temperature becomes, the lower the emission current at which angular emission anisotropy due to the lattice structure of LaB6crystal appears. The emission of 〈110〉 LaB6cathodes was found to be more affected by lattice structure than that of 〈110〉 LaB6cathodes. To obtain a uniform distribution beam it is more advantageous to use 〈100〉 LaB6cathodes than 〈110〉. Uniform angular emission were obtained with a 〈100〉 LaB6cathode of 100 μm tip radius even at an emission current of 700 μA and a tip temperature of 1500 °C. Under these conditions, the measured brightness and emittance were 3.9×105A/cm2 sr and 61 μm mrad, respectively.