The present invention provides a time setting system and method thereof that are capable of correctly setting time if a delay occurs in the transmission of time information. In the system for setting a master time outputted from a master apparatus to a slave time of a slave apparatus that counts time independently of the master apparatus, the slave apparatus has transmission section for transmitting master time request information to the master apparatus via a network and the master apparatus has an allowable range information acquisition section for acquiring allowable range information indicative of an allowable time in which the master time may be set to the slave time of the slave apparatus and transmission section for transmitting the master time and allowable range information to the slave apparatus. The slave apparatus obtains a time difference between a first slave time to be obtained before or after the transmission of master time request information and a second slave time to be obtained at reception of the master time and the allowable range information. If the allowable time is greater than the obtained time difference, the master time is set.