Cycle estimation device for pulse train signal, cycle estimation method for pulse train signal, and cycle estimation program for pulse train signal

A cycle estimation device (10) includes: a candidate cycle extraction unit (11) which extracts a candidate cycle that is a cycle determination target from an input time-series pulse train; a pulse train shape analysis unit (12) which converts arrangement of the time-series pulse train into numerical values on the basis of the extracted candidate cycle and outputs a constant that adjusts a random noise threshold value of pulse repetition interval (PRI) conversion in response to an index indicating a degree of concentration of calculated numerical values; and a cycle detection unit (13) which executes PRI conversion using a value of the candidate cycle and the constant and performs cycle determination and cycle value detection.