A data collection system includes sensors which are synchronized with each other and an optical signal distributor, wherein each of the sensors comprises a first delay unit which delays a second electrical signal for a first delay time set such that a sum of the first delay time and a first conversion time is same in all of the sensors, and the optical signal distributor comprises second delay units each of which delays a first electrical signal for a second delay time set such that all of sums of the second delay times and conversion times are same as each other.