A compact pump (10A, 10B, 10C) comprising: a hollow case (12, 12A, 12B) which is symmetrical with respect to a motor rotation axis; a diaphragm assembly which is disposed in the case at an upper position and includes first to Nth diaphragm units (221-1 to 221-3) which form first to Nth pump chambers (PC1 to PC3), respectively, N being an integer that is larger than or equal to 2; and a swing body which is disposed in the case at a lower position and moves the first to Nth diaphragm units in the top-bottom direction when swung by an eccentric rotary shaft, wherein: the first to Nth diaphragm units (221-1 to 221-3) have first to Nth through-holes (222-1a to 222-3a) at centers of bottom portions thereof, respectively; the swing body has first to Nth air introduction holes (244-1a to 244-3a) which communicate with the first to Nth through-holes (222-1a to 222-3a), respectively; the diaphragm assembly has first to Nth intake valve elements (222-1 to 222-3) which open and close the first to Nth air introduction holes (244-1a to 244-3a), respectively; the case (12, 12A, 12B) has an upper cover (16, 16A) which is provided at an upper portion of the case (12, 12A, 12B); the upper cover has an exhaust hole formed along the motor rotation axis and first to Nth ring-shaped recesses (162d1 to 162d3) which are disposed around and communicate with the exhaust hole; the upper cover (16, 16A) has first to Nth tubular inner wall surfaces (162-1a to 162-3a; 162A-1a to 162A-3a) which define the first to Nth ring-shaped recesses, respectively; the diaphragm assembly has first to Nth tubular exhaust valve elements (224-1 to 224-3) which are disposed in the first to Nth ring-shaped recesses in a state that the first to Nth tubular exhaust valve elements are in contact with the first to Nth tubular inner wall surfaces, respectively; and the pump being characterized in that the diaphragm assembly has a rib which is disposed at a center of the diaphragm assembly in a vicinity of the exhaust hole and connects center-side outer wall surfaces of the first to Nth tubular exhaust valve elements. a hollow case (12, 12A, 12B) which is symmetrical with respect to a motor rotation axis; a diaphragm assembly which is disposed in the case at an upper position and includes first to Nth diaphragm units (221-1 to 221-3) which form first to Nth pump chambers (PC1 to PC3), respectively, N being an integer that is larger than or equal to 2; and a swing body which is disposed in the case at a lower position and moves the first to Nth diaphragm units in the top-bottom direction when swung by an eccentric rotary shaft, wherein: the first to Nth diaphragm units (221-1 to 221-3) have first to Nth through-holes (222-1a to 222-3a) at centers of bottom portions thereof, respectively; the swing body has first to Nth air introduction holes (244-1a to 244-3a) which communicate with the first to Nth through-holes (222-1a to 222-3a), respectively; the diaphragm assembly has first to Nth intake valve elements (222-1 to 222-3) which open and close the first to Nth air introduction holes (244-1a to 244-3a), respectively; the case (12, 12A, 12B) has an upper cover (16, 16A) which is provided at an upper portion of the case (12, 12A, 12B); the upper cover has an exhaust hole formed along the motor rotation axis and first to Nth ring-shaped recesses (162d1 to 162d3) which are disposed around and communicate with the exhaust hole; the upper cover (16, 16A) has first to Nth tubular inner wall surfaces (162-1a to 162-3a; 162A-1a to 162A-3a) which define the first to Nth ring-shaped recesses, respectively; the diaphragm assembly has first to Nth tubular exhaust valve elements (224-1 to 224-3) which are disposed in the first to Nth ring-shaped recesses in a state that the first to Nth tubular exhaust valve elements are in contact with the first to Nth tubular inner wall surfaces, respectively; and the pump being characterized in that the diaphragm assembly has a rib which is disposed at a center of the diaphragm assembly in a vicinity of the exhaust hole and connects center-side outer wall surfaces of the first to Nth tubular exhaust valve elements. the first to Nth diaphragm units (221-1 to 221-3) have first to Nth through-holes (222-1a to 222-3a) at centers of bottom portions thereof, respectively; the swing body has first to Nth air introduction holes (244-1a to 244-3a) which communicate with the first to Nth through-holes (222-1a to 222-3a), respectively; the diaphragm assembly has first to Nth intake valve elements (222-1 to 222-3) which open and close the first to Nth air introduction holes (244-1a to 244-3a), respectively; the case (12, 12A, 12B) has an upper cover (16, 16A) which is provided at an upper portion of the case (12, 12A, 12B); the upper cover has an exhaust hole formed along the motor rotation axis and first to Nth ring-shaped recesses (162d1 to 162d3) which are disposed around and communicate with the exhaust hole; the upper cover (16, 16A) has first to Nth tubular inner wall surfaces (162-1a to 162-3a; 162A-1a to 162A-3a) which define the first to Nth ring-shaped recesses, respectively; the diaphragm assembly has first to Nth tubular exhaust valve elements (224-1 to 224-3) which are disposed in the first to Nth ring-shaped recesses in a state that the first to Nth tubular exhaust valve elements are in contact with the first to Nth tubular inner wall surfaces, respectively; and the pump being characterized in that the diaphragm assembly has a rib which is disposed at a center of the diaphragm assembly in a vicinity of the exhaust hole and connects center-side outer wall surfaces of the first to Nth tubular exhaust valve elements.