Abstract: Oil strainer has a housing having a suction port and a discharge port and a filtration element dividing an inside of the housing into a suction port side and a discharge port side. The filtration element has a first filtration member having a coarse filter, a second filtration member having a fine filter and stacked at an upstream side or a downstream side of the first filtration member and a retainer plate having a plurality of oil pass openings and retaining the first and second filtration members. The retainer plate is stacked at a downstream side of the first and second filtration members. The second filtration member has at least one opening portion so that a part of the oil bypasses the second filtration member. One of the first and second filtration members has protruding and depressed portions that touch the other of the first and second filtration members.