A manual breast pump, comprising: a main body having a passage through which extracted breast milk passes; a hood connected to the main body and placed onto a breast; a diaphragm provided to the main body and generating a negative pressure in the passage; a holding member attached to the main body and provided to be rotatable with respect to the main body; and a handle for being operated thereby deforming the diaphragm, the handle being held by the holding member, wherein when the holding member rotates with respect to the main body, the handle rotates with respect to the main body together with the holding member, wherein the holding member has: an attachment portion fitted therein so as to be rotatable with respect to the main body; and an extension portion extending from the attachment portion and supporting the handle in a reciprocable manner, and wherein the main body has: a diaphragm mounting portion above which the diaphragm is mounted, and a receiving portion provided in a position downwardly away from the diaphragm mounting portion, characterized in that: the attachment portion is installed in a sandwiched position between the diaphragm mounting portion and the receiving portion; the main body has a guide portion provided between the diaphragm mounting portion and the receiving portion; and the attachment portion has a rotation stabilizing portion installed in a sandwiched position between the diaphragm mounting portion and the guide portion. a main body having a passage through which extracted breast milk passes; a hood connected to the main body and placed onto a breast; a diaphragm provided to the main body and generating a negative pressure in the passage; a holding member attached to the main body and provided to be rotatable with respect to the main body; and a handle for being operated thereby deforming the diaphragm, the handle being held by the holding member, wherein when the holding member rotates with respect to the main body, the handle rotates with respect to the main body together with the holding member, wherein the holding member has: an attachment portion fitted therein so as to be rotatable with respect to the main body; and an extension portion extending from the attachment portion and supporting the handle in a reciprocable manner, and wherein the main body has: a diaphragm mounting portion above which the diaphragm is mounted, and a receiving portion provided in a position downwardly away from the diaphragm mounting portion, characterized in that: the attachment portion is installed in a sandwiched position between the diaphragm mounting portion and the receiving portion; the main body has a guide portion provided between the diaphragm mounting portion and the receiving portion; and the attachment portion has a rotation stabilizing portion installed in a sandwiched position between the diaphragm mounting portion and the guide portion. an attachment portion fitted therein so as to be rotatable with respect to the main body; and an extension portion extending from the attachment portion and supporting the handle in a reciprocable manner, and wherein the main body has: a diaphragm mounting portion above which the diaphragm is mounted, and a receiving portion provided in a position downwardly away from the diaphragm mounting portion, characterized in that: the attachment portion is installed in a sandwiched position between the diaphragm mounting portion and the receiving portion; the main body has a guide portion provided between the diaphragm mounting portion and the receiving portion; and the attachment portion has a rotation stabilizing portion installed in a sandwiched position between the diaphragm mounting portion and the guide portion. a diaphragm mounting portion above which the diaphragm is mounted, and a receiving portion provided in a position downwardly away from the diaphragm mounting portion, characterized in that: the attachment portion is installed in a sandwiched position between the diaphragm mounting portion and the receiving portion; the main body has a guide portion provided between the diaphragm mounting portion and the receiving portion; and the attachment portion has a rotation stabilizing portion installed in a sandwiched position between the diaphragm mounting portion and the guide portion. the attachment portion is installed in a sandwiched position between the diaphragm mounting portion and the receiving portion; the main body has a guide portion provided between the diaphragm mounting portion and the receiving portion; and the attachment portion has a rotation stabilizing portion installed in a sandwiched position between the diaphragm mounting portion and the guide portion.