To provide a strainer device which enables installation in a position near a water spray head in a little space, and also reduces pressure drop.

A water spray head 20 is arranged at a tip of head pipings 14 and 18 brought down by an L shape from a water spray piping 10 in a tunnel, and pressurized water is sprayed on a water-discharge space in a tunnel from the water spray head 20 in case of fire. A strainer device 16 is prepared at an L shape connection part of the head pipings 14 and 18. The strainer device 16 forms a first end connection 24 used as an input at an upper part of a strainer body 22, forms a second end connection 26 used as an outlet at a lateral direction, and further, forms a filtering object outlet 28 at a lower part which faces the input, wherein a filtering object 30 using a cylinder screen is contained from the filtering object outlet 28 to the strainer body 22 to be freely taken out or put in, and a lid member 32 is prepared at the filtering object outlet 28 of the strainer body 22 to be freely attached or detached.