A centrifugal pump apparatus including a housing having first and second chambers (7, 8) partitioned from each other by a diaphragm, an impeller rotatably provided in said first chamber along said diaphragm, for delivering liquid by centrifugal force during rotation, and a drive unit (18 to 20) provided in said second chamber for driving said impeller to rotate with said diaphragm being interposed, comprising: a first magnetic element (15a, 15b) provided in one surface of said impeller; a second magnetic element (16a, 16b) provided in an inner wall of said first chamber facing the one surface of said impeller, for attracting said first magnetic element (15a, 15b); and a third magnetic element provided in the other surface of said impeller, during rotation of said impeller, first attractive force between said first and second magnetic elements (15a, 15b, 16a, 16b) and second attractive force between said third magnetic element and said drive unit (18 to 20) being balanced with each other substantially in a center of a movable range of said impeller in said first chamber, an amount of change in said first attractive force with respect to an amount of eccentricity in a radial direction of said impeller being substantially equal to an amount of change in said second attractive force with respect to the amount of eccentricity in the radial direction of said impeller, and a first groove for hydrodynamic bearing being formed in one surface of said impeller or in the inner wall of said first chamber facing the one surface and a second groove for hydrodynamic bearing being formed in the other surface of said impeller or in said diaphragm facing the other surface, wherein said third magnetic element includes a plurality of magnets arranged along a single, identical circle such that adjacent magnetic polarities are different from each other, and said drive unit (18 to 20) includes a plurality of coils provided to face said plurality of magnets, for generating rotating magnetic field, and wherein said second attractive force is adjusted by varying a phase of a current fed to said plurality of coils. a first magnetic element (15a, 15b) provided in one surface of said impeller; a second magnetic element (16a, 16b) provided in an inner wall of said first chamber facing the one surface of said impeller, for attracting said first magnetic element (15a, 15b); and a third magnetic element provided in the other surface of said impeller, during rotation of said impeller, first attractive force between said first and second magnetic elements (15a, 15b, 16a, 16b) and second attractive force between said third magnetic element and said drive unit (18 to 20) being balanced with each other substantially in a center of a movable range of said impeller in said first chamber, an amount of change in said first attractive force with respect to an amount of eccentricity in a radial direction of said impeller being substantially equal to an amount of change in said second attractive force with respect to the amount of eccentricity in the radial direction of said impeller, and a first groove for hydrodynamic bearing being formed in one surface of said impeller or in the inner wall of said first chamber facing the one surface and a second groove for hydrodynamic bearing being formed in the other surface of said impeller or in said diaphragm facing the other surface, wherein said third magnetic element includes a plurality of magnets arranged along a single, identical circle such that adjacent magnetic polarities are different from each other, and said drive unit (18 to 20) includes a plurality of coils provided to face said plurality of magnets, for generating rotating magnetic field, and wherein said second attractive force is adjusted by varying a phase of a current fed to said plurality of coils.