A bulk acoustic wave resonator includes a substrate including a first via and a second via, a lower electrode connection member, a lower electrode, a piezoelectric layer, an upper electrode, and an upper electrode connection member spaced apart from the lower electrode connection member. The lower electrode, the piezoelectric layer, and the upper electrode constitute a resonant portion. The lower electrode connection member electrically connects the lower electrode to the first via and supports a first edge portion of the resonant portion. The upper electrode connection member electrically connects the upper electrode to the second via and supports a second edge portion of the resonant portion. Either one or both of the upper electrode connection member and the lower electrode connection member includes a respective extension portion connected to a respective one of the first via and the second via that is disposed below the resonant portion.