To provide a DPF cleaning device which can surely remove ash deposited in the vicinity of a seam sealing part at the exhaust side of a DPF, and its cleaning method.

A nozzle moving device has a function for inserting the tip of a nozzle (21) into the inside (5) of a cell of the DPF (10) up to a position exceeding at least the seam sealing part when moving the nozzle (21) to a direction in which the nozzle approximates the DPF (10), and the nozzle (21) has a function for injecting cleaning fluids injected from injection holes (21a, 21b) at the tip of the nozzle (21) to a direction on a plane orthogonal to the center axis of the nozzle (21), or to a direction in which the nozzle (21) is inclined to a direction in which the nozzle is inserted into the inside (5) of the cell rather than the plane.