An evaporative fuel processing device for determining a leak of an evaporation piping system also determined pump abnormality by including a pump, a pressure sensor and an abnormality determiner, i.e., by pressuring/de-pressuring the system to a positive/negative value against an atmospheric pressure for leak determination, by detecting a pressure of the system, and by determining a leak hole in a normal leak determination mode based on an absolute value of the detected pressure reaching or not reaching a target value after pump operation and based on an assumption that the pump is normal. Specifically, after lapse of a determination time from a pump stop, the absolute value equal to or less than a normal leak determination threshold value is determined that a leak hole is present in the system. Further, the absolute value not reaching the target value even after pump operation triggers a pump abnormality determination mode.