A method of transmitting power of a wireless power transmitter, including a receiving phase of receiving a signal including an FOD status packet from a wireless power receiver; a first determination phase of determining whether a foreign object is present in a charging area of the wireless power transmitter based on the FOD status packet; a power control phase of controlling power transmission in a first power transfer mode upon determining that the foreign object is present in the charging area in the first determination phase, or controlling power transmission in a second power transfer mode upon determining that the foreign object is not present in the charging area in the first determination phase; and a second determination phase of determining whether the foreign object is present in the charging area based on information other than information included in the FOD status packet, while controlling power transmission in one of the first power transfer mode and the second power transfer mode by the power control phase.