A time series data processing device for processing time series data that is a sequence of data received from a system that is a processing target over time includes a time series data search processing unit that receives, for details of the time series data and occurrence time information, a time series data search condition including events of a plurality of the time series data and an interval condition that is a condition of time intervals of the events occurring, and changes the interval condition using an allowable time lag that is allowable time of a set time lag in a transmission source of the time series data to thereby reflect the set time lag in the time series data search condition; and a data monitoring unit that monitors the time series data received from the system that is the processing target, using the time series data search condition changed by the time series data search processing unit.