The time evolution of bubble motion was studied in continuous single-bubble flow systems. Dynamic changes in rise velocity, shape and orientation of bubbles were simultaneously measured using a flow visualization method. Both deterministic chaos and stochastic analyses were used to diagnose bubble dynamics in gas-liquid two-phase systems. The bubbles were found to have chaotic fluctuations in shape and rise velocity. The Kolmogorov entropy and the correlation dimension of the attractor reconstructed from the time-series data of bubble-shape indices and velocity components by the embedding method were found to be positive and very high, indicating the chaotic-time evolution of bubble motion. On the other hand, the bubble inclined angle exhibited a periodic variation in bubble orientation, reflecting the zigzag motion of rising bubbles. The fluctuation in bubble-rise velocity can be considered to take place in the streamwise direction due to the oscillation of drag force associated with the bubble-shape fluctuation.