A housing has a compression chamber and a first passage, through which the compression chamber communicates with an accumulation chamber. A discharge valve is provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the compression chamber. A second passage is configured to communicate the accumulation chamber with the compression chamber via the discharge valve. A valve element allows fuel flow from the accumulation chamber to the compression chamber. A biasing unit biases the valve element to seat the valve element on a valve seat of the second passage. The sidewall of the valve element and the inner wall defining the second passage therebetween define a throttle midway through the second passage for restricting fuel flow from the accumulation chamber to the compression chamber.