In a balanced-unbalanced type multi-mode thin film elastic wave resonator filter (100), the area of a first lower electrode (102) is substantially equal to the total of the areas of a second and a third lower electrode (104, 106) and an area between the second and the third lower electrode (104, 106). The area of a first upper electrode (103) is substantially equal to the total of the areas of a second and a third upper electrode (105,107) and the area between the second and the third upper electrode (105, 107). The third lower electrode (106) opposes to the second upper electrode (105) while the third upper electrode (107) opposes to the second lower electrode (104). A part of the second lower electrode (104) opposes to a part of the second upper electrode (105).