A time stamp adding device includes: PCR_PID detecting means for detecting a PCR_PID included in a PMT by searching TS packets included in a TS from the head of the TS including TS packets having no time stamp, input from the outside and transmitted in a MPEG2-TS format and analyzing the resulting PMT; PCR detecting means for detecting values of PCRs included between the head of the TS and the PMT and position information of the PCRs and detecting values of all PCRs in the TS packets between the PMT and the tail of the TS and position information of the PCRs in the TS; time interval calculating means for calculating a time interval for adding a time stamp and a value of the time stamp based on the PCR values; and time stamp adding means for adding the time stamps to the TS packets having no time stamp based on the time interval.