Strainer

A strainer wherein front and rear end portions which a tubular casing has in an axial direction are respectively provided with an inlet connected to an upstream side of the piping and an outlet connected to a downstream side of the piping, the inlet of the front end portion and the outlet of the rear end portion each are formed to have a diameter smaller than an inner diameter of the casing, a barrier that divides in two a linear channel between the inlet and the outlet is provided on an outlet side vertically throughout in the casing so as to face the inlet, a filter portion surrounding the inlet is constituted by the barrier, a pair of screens laterally opposing each other arranged at a predetermined interval, and upper and lower portions of an inner surface of an outer wall of the casing, and upper and lower regions of the outer wall are provided with opening portions with lids which make an inside of the filter portion communicate with an outside.