A pump comprising: a pump body that includes a suction path provided with a suction port through which liquid is sucked, and a discharge path provided with a first discharge port through which sucked liquid is discharged; an impeller stored in a pump chamber formed inside the pump body; and a shaft that supports the impeller (709 such that the impeller is rotatable, wherein a pump channel extending from the suction port to the first discharge port is formed inside the pump body, wherein the pump channel includes the suction path, an impeller channel which is formed inside the impeller and into which liquid in the suction path is introduced, a volute portion which is formed on a radially outer side of the impeller and into which liquid in the impeller channel is introduced, and the discharge path into which liquid in the volute portion is introduced, a liquid separation reduction structure that reduces separation of liquid flowing in the pump channel is provided in the pump channel, an opening is formed on a radially inner side of the volute portion, the opening facing a second discharge port formed on a radially outer side of the impeller channel, an inclined surface is formed in an inner surface of the volute portion, the inclined surface being inclined such that an axial length of the volute portion increases from an opening-side end edge of the volute portion toward a radially outer side of the volute portion, the liquid separation reduction structure includes the inclined surface, and the inclined surface is configured such that a radial cross section of the volute portion constitutes a straight line, the discharge path is configured such that a contour shape of a channel cross section of the discharge path gradually changes into a perfect circle from an end point of the volute portion toward the first discharge port, and the liquid separation reduction structure includes the discharge path, the pump being characterized in that the pump channel includes a straightening portion formed between the impeller channel and the volute portion, the straightening portion being configured such that a boundary of the straightening portion, when seen in a cross-section by a plane containing the rotation axis of the pump, constitutes a radially extending straight line; the liquid separation reduction structure includes the straightening portion, and a channel cross-sectional area of the discharge path linearly increases from the end point of the volute portion to the first discharge port. a pump body that includes a suction path provided with a suction port through which liquid is sucked, and a discharge path provided with a first discharge port through which sucked liquid is discharged; an impeller stored in a pump chamber formed inside the pump body; and a shaft that supports the impeller (709 such that the impeller is rotatable, wherein a pump channel extending from the suction port to the first discharge port is formed inside the pump body, wherein the pump channel includes the suction path, an impeller channel which is formed inside the impeller and into which liquid in the suction path is introduced, a volute portion which is formed on a radially outer side of the impeller and into which liquid in the impeller channel is introduced, and the discharge path into which liquid in the volute portion is introduced, a liquid separation reduction structure that reduces separation of liquid flowing in the pump channel is provided in the pump channel, an opening is formed on a radially inner side of the volute portion, the opening facing a second discharge port formed on a radially outer side of the impeller channel, an inclined surface is formed in an inner surface of the volute portion, the inclined surface being inclined such that an axial length of the volute portion increases from an opening-side end edge of the volute portion toward a radially outer side of the volute portion, the liquid separation reduction structure includes the inclined surface, and the inclined surface is configured such that a radial cross section of the volute portion constitutes a straight line, the discharge path is configured such that a contour shape of a channel cross section of the discharge path gradually changes into a perfect circle from an end point of the volute portion toward the first discharge port, and the liquid separation reduction structure includes the discharge path, the pump being characterized in that the pump channel includes a straightening portion formed between the impeller channel and the volute portion, the straightening portion being configured such that a boundary of the straightening portion, when seen in a cross-section by a plane containing the rotation axis of the pump, constitutes a radially extending straight line; the liquid separation reduction structure includes the straightening portion, and a channel cross-sectional area of the discharge path linearly increases from the end point of the volute portion to the first discharge port.