Sufficient knowledge of bubble-induced turbulence (B.I.T.) is indispensable to develop an accurate turbulence model in a gas-liquid two-phase bubbly flow. In this study, we measured turbulence intensities and Reynolds stresses in air-water bubbly flow in a vertical pipe under the condition of a low liquid Reynolds number (Re=900). To enable the LDV measurement of Reynolds stresses, we could confirm that (1) turbulent kinetic energy of B.I.T. is proportional to local void fraction, (2) the ratio among axial, radial and azimuthal components of turbulence intensity is 2 : 1 : 1 and (3) the Reynolds shear stress of B. I. T. is well correlated with the void fraction gradient.