This study investigated the effects of the difference of beam-pointing directions on the Doppler measurements from a spaceborne Ku-band precipitation radar. The Doppler measurement system was a displaced phase center antenna (DPCA) using two antennas that are displaced in the along-track direction. When the beam-pointing directions of the two antennas deviate, Doppler measurements can degrade. The well-known formula for the uncertainty in Doppler velocity measurement is extended to include the effect of the difference of the beam-pointing directions, and a simulation confirmed the formula. The results show that the uncertainty increases from 0.21 to 0.38 m/s for a case of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S/N = 20$ </tex-math></inline-formula> dB when one antenna footprint center is displaced from the other by half of the half-power beamwidth.