A failure detection apparatus for a particulate filter in which a failure of the particulate filter arranged in an exhaust passage of an internal combustion engine is detected, said failure detection apparatus for a particulate filter comprising: a filter regeneration processing execution part that executes filter regeneration processing to remove particulate matter deposited on said particulate filter; an inflow PM amount obtaining part that obtains an amount of inflow particulate matter which is an amount of the particulate matter flowing into said particulate filter; a PM sensor that detects an amount of outflow particulate matter which is an amount of the particulate matter flowing out from said particulate filter; and a PM trapping efficiency calculation part that calculates a PM trapping efficiency, which is a proportion of an amount of particulate matter trapped by said particulate filter with respect to the amount of inflow particulate matter, based on the amount of inflow particulate matter obtained by said inflow particulate matter obtaining part, and the amount of outflow particulate matter detected by said PM sensor; characterized in that said failure detection apparatus for a particulate filter further comprises: a failure detection part that makes a determination that a failure has occurred in said particulate filter, in cases where there has appeared a tendency for the PM trapping efficiency calculated by said PM trapping efficiency calculation part to decrease during a period of time beginning after the execution of the filter regeneration processing by said filter regeneration processing execution part is completed and ending when the execution of the following filter regeneration processing is started, and the decrease level of the PM trapping efficiency during a fixed period of time is equal to or more than a predetermined reference level. a filter regeneration processing execution part that executes filter regeneration processing to remove particulate matter deposited on said particulate filter; an inflow PM amount obtaining part that obtains an amount of inflow particulate matter which is an amount of the particulate matter flowing into said particulate filter; a PM sensor that detects an amount of outflow particulate matter which is an amount of the particulate matter flowing out from said particulate filter; and a PM trapping efficiency calculation part that calculates a PM trapping efficiency, which is a proportion of an amount of particulate matter trapped by said particulate filter with respect to the amount of inflow particulate matter, based on the amount of inflow particulate matter obtained by said inflow particulate matter obtaining part, and the amount of outflow particulate matter detected by said PM sensor; characterized in that said failure detection apparatus for a particulate filter further comprises: a failure detection part that makes a determination that a failure has occurred in said particulate filter, in cases where there has appeared a tendency for the PM trapping efficiency calculated by said PM trapping efficiency calculation part to decrease during a period of time beginning after the execution of the filter regeneration processing by said filter regeneration processing execution part is completed and ending when the execution of the following filter regeneration processing is started, and the decrease level of the PM trapping efficiency during a fixed period of time is equal to or more than a predetermined reference level. a failure detection part that makes a determination that a failure has occurred in said particulate filter, in cases where there has appeared a tendency for the PM trapping efficiency calculated by said PM trapping efficiency calculation part to decrease during a period of time beginning after the execution of the filter regeneration processing by said filter regeneration processing execution part is completed and ending when the execution of the following filter regeneration processing is started, and the decrease level of the PM trapping efficiency during a fixed period of time is equal to or more than a predetermined reference level.