A washer pump includes a case partitioned into a motor chamber, which accommodates an armature rotated when it is electrically energized, and partitioned into a pump chamber, which accommodates an impeller rotated being coupled to an armature shaft of the armature, wherein washing liquid is sucked into the pump chamber from a liquid suction port, which is communicated with the pump chamber, by the rotation of the impeller, and the washing liquid is discharged from a liquid discharge port which is communicated with the pump chamber, and the washer pump is characterized in that: a ventilation hole is provided on a partition wall to partition the pump chamber and the liquid suction port, a filter for filtering the washing liquid is detachably attached to the liquid suction port, an air passage is provided in the filter, and the air passage is communicated with the ventilation hole.