1. A malfunction condition judgment apparatus (MCJA) that judges at least one malfunction condition (MC) of an observed object based on a change of observed values observed from the observation object, comprising: an acquiring unit operable to acquire time series data of values for each of a plurality of variables that has a plurality of observed values observed from the observation object as a value; a statistic computing unit operable to calculate, with respect to each of the variables, a statistic defining a probability density function of that variable at a point of time (T1), based on the value of that variable at T1 and that statistic at a point of time prior to T1; a dissimilarity computing unit operable to calculate, with respect to each of the variables, dissimilarity showing an extent of variation between the statistic calculated for that variable and a statistic of a criterial probability density function predetermined corresponding to that variable; and an extracting unit operable to pick up, out of the plurality of variables, a variable in which the calculated dissimilarity is larger than a predetermined reference value, as the variable by which MC of the observed object is detected.