A detecting apparatus that detects a degree of correlation between first events and second events repeatedly occurring in an observed apparatus, where the events refer to changes in the state of hardware or software in the observed apparatus, characterised by comprising: an acquiring unit that acquires second event count values each indicating the number of second events occurring during each first period between each first event and the first event next thereto and further acquires first event count values each indicating the number of first events occurring during each second period between each second event and the second event next thereto, a measuring unit that measures an observed number of each second event count value derived from the number of times the second event count value is observed, and further measures an observed number of each first event count value derived from the number of times the first event count value is observed, where the observed number could be any of various expression forms in which a data value varies depending on the number of times an event value is observed; and a calculating unit that calculates the degree of correlation between the first events and the second events based on the observed number of each second event count value, and each first event count value, wherein to obtain the correlation between the events, the calculating unit uses the following formula: C AB = 1 ∑ i = 1 NB ∑ j = 1 NA Nonzero F AB i × Nonzero F BA j where ABi represents an i-th second event count value (i is an integer equal to or greater than one), and F(ABi) represents the frequency of occurrence of the i-th second event count value, where BAj represents a j-th first event count value (j is an integer equal to or greater than one), and F(BAj) represents the frequency of occurrence of the j-th first event count value, and where Nonzero(x) function returns 0 if x is zero, and returns 1 if x is non-zero, and where N A represents the total number of occurrences of the first events and N B represents the total number of occurrences of the second events. an acquiring unit that acquires second event count values each indicating the number of second events occurring during each first period between each first event and the first event next thereto and further acquires first event count values each indicating the number of first events occurring during each second period between each second event and the second event next thereto, a measuring unit that measures an observed number of each second event count value derived from the number of times the second event count value is observed, and further measures an observed number of each first event count value derived from the number of times the first event count value is observed, where the observed number could be any of various expression forms in which a data value varies depending on the number of times an event value is observed; and a calculating unit that calculates the degree of correlation between the first events and the second events based on the observed number of each second event count value, and each first event count value, wherein to obtain the correlation between the events, the calculating unit uses the following formula: C AB = 1 ∑ i = 1 NB ∑ j = 1 NA Nonzero F AB i × Nonzero F BA j