A synchronization method of a first depth sensing apparatus includes: transmitting a first optical signal to measure a distance to an object; receiving the first optical signal reflected by the object; when recognition of the received first optical signal fails, stopping transmission of the first optical signal and generating first synchronization information for synchronization with at least one second depth sensing apparatus; receiving a third optical signal for synchronization with the first depth sensing apparatus, which is transmitted by the at least one second depth sensing apparatus, and decoding the received third optical signal to extract at least one piece of second synchronization information; determining a time point at which and a cycle in which to re-transmit the first optical signal, based on the first synchronization information and the at least one piece of second synchronization information; and re-transmitting the first optical signal at the determined time point and cycle.