This paper reports the analysis of wind effect and water discharge effect on constant flow, using tidal current and sea wind data obtained at Off-Sennan in the
south-west of Osaka Bay and discharge data of Yodo River at Hirakata for the period from January 1978 to November 1981. Yodo River is the biggest of all rivers flowing into Osaka Bay. Tidal currents were measured by ultra-sonic current meters in three layers, each 3, 9, 16 meters below the datum level for soundings.
　The absolute value of constant flow, obtained by annual data harmonic analysis, shows strong relation to water discharge into Osaka Bay. It is found by principle component analysis that east and north components of constant flow in each layer, from 90, 30, 15-day data harmonic analysis, show positive relation to both components of sea wind and negative relation to the discharge of Yodo River. When data duration is shortened, the relation betweem constant flow and discharge becomes weak, but one between constant flow and sea wind is unchanged.
　The veriation of constant flow, defined as 25-hour running mean flow vector, is well explained by the multiple regression, using 24-hour running mean vector of sea wind as the predictor variable.