A method for controlling a washing machine having a drying function is disclosed. The method for controlling the washing machine having a drying function includes: a) dehydrating laundry if a command for performing a drying operation is inputted by a user; and b) drying the laundry after the dehydrating step. The dehydrating step a) includes: measuring time until a rotational velocity of a drum reaches a predetermined velocity; calculating an amount of the laundry based on the measured time; determining a dehydration velocity and dehydration time according to the calculated amount of the laundry; and rotating the drum at the dehydration velocity for the dehydration time. The drying step b) includes: hot-air drying the laundry by operating a heater and a blower fan to supply hot air into the drum until dryness of the laundry reaches a predetermined target dryness; and if the dryness of the laundry reaches the predetermined target dryness, cool-air drying the laundry by stopping operation of the heater while keeping operation of the blower fan to supply air of low temperature into the drum for a predetermined time.