To provide a rainwater splash preventing device reducible in manufacturing cost while having excellent workability and large draining ability in a drain device for a junction.

A guide inclined conical surface 22 with its upper end formed as a lead-in port 21a with a diameter larger than the outer diameter of a leader pipe 8 and with its lower end formed as a lead-out port 21b with a diameter smaller than or almost equal to the upper opening diameter of a drain pipe part 3, is integrally formed inside a strainer 20A. The stainer 20A is mounted in the state of the lead-in port 21a concentrically facing the lower part position of the leader pipe 8, and the lower part of the lead-out port 21b concentrically facing the drain pipe part 3 to form a required flow clearance (s) communicating with the outside, between the opening edge of the drain pipe part 3 and the lower part of the lead-out port 21b.