A control method of a washing machine, in which a hydraulic pressure of water supplied into the washing machine is estimated, enabling sensing of a laundry weight and measurement of a supply amount of the water. The control method includes calculating a first water supply time required to initially supply water to a setup water level, calculating a second water supply time required to additionally supply water according to a variation in water level due to laundry wetting after the initial supply of water, sensing a laundry weight according to a ratio of the first water supply time to the second water supply time, and measuring a flow rate of water using the amount of water supplied to the setup water level and the laundry weight data.