Velocities bf single particles (magnetic tracer particles) were measured in the draft tube region and annular region of a draft-tube bubble columns by use of the magnet-detector coil technique. The relative particle to liquid velocity was also obtained. The observed distribution of particle velocity was broader than that of liquid velocity. The relative particle to liquid velocity depended significantly on superficial gas velocity. Those for the draft tube region had minimums with increasing gas velocity, while those for the annular region decreased monotonously. The effective drag coefficients for the particles were correlated with particle Reynolds number and gas holdup.