Wireless power transmitting unit, wireless power receiving unit, and control methods thereof

A control method of a wireless power receiving unit receiving charging power from a wireless power transmitting unit to perform wireless charging is provided. The control method includes receiving the charging power from the wireless power transmitting unit; detecting a change in a wireless charging environment; generating a message notifyng of the change in the wireless charging environment; and transmitting the message notifyng of the change in the wireless charging environment to the wireless power transmitting unit.