Relating to a technology for separating a suspended matter in a suspension using ultrasonic waves, a technology that can realize high separation ability capable of highly efficient separation of the suspended matter in the suspension is provided. A suspension flow-through separation apparatus includes a flow-through separator including a flow-through separation unit. The flow-through separation unit includes a cavity structure that functions as a channel through which a suspension flows, a side surface portion which extends in an x-direction of the cavity structure, a supply port which is provided at one side surface portion, an outlet port which is provided at the other side surface portion, two planar portions that extend in a y-direction in the cavity structure and face to each other, and an ultrasonic oscillator that is provided at least one of two planar portions, and emits ultrasonic waves to the channel. The suspended matter in the suspension is captured by the ultrasonic waves and separated in a z-direction that is a vertical direction while the suspension flows through the channel of the flow-through separator. A first angle formed by the x-direction or the y-direction and a flow-through direction corresponding to a straight line connecting a center point of the supply port and a center point of the outlet port is an acute angle.