To provide a drying filter capable of easily and automatically removing waste cloth and cotton dust.

In order to easily remove the waste cloth and the cotton dust, the drying filter is horizontally disposed, a blowing air entrance and a blowing air exit are disposed so as to blow air from a blowing fan from the lower surface part to the upper surface part of the drying filter, a discharge path is provided on the lower surface part and a washing water shower port is provided on the upper surface part. By the configuration, washing water is directly jetted from the washing water shower port to the drying filter from a direction opposite to the direction that the waste cloth and the cotton dust clog and deposit when blowing air to remove the waste cloth and the cotton dust deposited in the drying filter. The discharge path is provided on the lower surface part where the waste cloth and the cotton dust flow down, and they are automatically removed and discharged through the discharge path after drying is ended or in a step other than a drying step.