To purify raw water by sucking action of a user by constituting a purifying device equipped with a water inlet to be dipped in raw water, with a sucking port communicated to the water inlet and to be sucked by a user, and with at least a filter to purify the raw water into drink water between the water inlet and the sucking port.

This portable water purifying device A is equipped with a water inlet 1 to be dipped in raw water W, a sucking port 2 communicated to the water inlet 1 and to be sucked by a user, and a filter 4 to purify the raw water W into drink water between the inlet 1 and the sucking port 2. The raw water W from river or lake is introduced through the water inlet 1 into the filter 4. The sucking port 2 is formed into a size like a straw or mouth piece of a tube instrument which can be held by a human mouth and which makes sucking easy, and is used to introduced the drink water purified by the filter 4 to the mouth of the user. The filter 4 may have both of a purifying effect of the raw water W and a preventing effect against mixing of foreign matters, however, it is preferable to separate the purifying filter 14 from a filter 24 to remove foreign matters.