The motion of atom is the main factor that limits the precision of the time/frequency standard. AIST has developed a cesium atomic fountain frequency standard, in which the motion of atom is frozen to below 1 μK by laser cooling. Due to the low temperature, the linewidth of Ramsey fringes, to which the microwave frequency is stabilized, is reduced to 0.8 Hz. The evaluation of the new frequency standard is in progress, and a frequency stability of σ (τ) = 4.7 × 10^-13 × τ^-1/2 is obtained (Fig. 1).