An electromagnetic vibrating diaphragm pump comprising: magnetic coil portions connected to an alternating-current power source, an oscillator being equipped with a permanent magnet and being driven so as to make a reciprocating motion by applying an alternating voltage to the magnetic coil portions, diaphragms connected to both ends of the oscillator, and pump casings provided with a suction port and an exhaust port for a fluid, wherein each of the pump casings is provided with: a suction chamber provided on an upper side of the pump casing and communicating with the suction port, an exhaust chamber provided on a lower side of the pump casing and communicating with the exhaust port, and a compression chamber communicating with the suction chamber via a suction valve and communicating with the exhaust chamber via an exhaust valve, wherein an inside pressure increases and decreases due to deformation of the diaphragm according to the reciprocating motion of the oscillator, characterized by: a first communicating passage being provided with the suction valve and communicating between the suction chamber and the compression chamber is formed at a bottom end of a partition wall between the suction chamber and the compression chamber, a bottom portion inside the suction chamber slopes down toward the first communicating passage such that the compression chamber side thereof is lower than the suction chamber side, and a bottom portion of the first communicating passage slopes down such that its compression chamber side is made lower, a second communicating passage being provided with the exhaust valve and communicating between the exhaust chamber and the compression chamber is formed at a bottom end of a partition wall between the exhaust chamber and the compression chamber, a bottom portion inside the compression chamber slopes down toward the second communicating passage such that the exhaust chamber side thereof is lower than the compression chamber side, and a bottom portion of the second communicating passage slopes down such that its exhaust chamber side is made lower, and a bottom portion inside the exhaust chamber slopes down toward the exhaust port such that the exhaust port side thereof is made lower, and the exhaust port slopes down such that an outlet side thereof is made lower. magnetic coil portions connected to an alternating-current power source, an oscillator being equipped with a permanent magnet and being driven so as to make a reciprocating motion by applying an alternating voltage to the magnetic coil portions, diaphragms connected to both ends of the oscillator, and pump casings provided with a suction port and an exhaust port for a fluid, a suction chamber provided on an upper side of the pump casing and communicating with the suction port, an exhaust chamber provided on a lower side of the pump casing and communicating with the exhaust port, and a compression chamber communicating with the suction chamber via a suction valve and communicating with the exhaust chamber via an exhaust valve, wherein an inside pressure increases and decreases due to deformation of the diaphragm according to the reciprocating motion of the oscillator, a first communicating passage being provided with the suction valve and communicating between the suction chamber and the compression chamber is formed at a bottom end of a partition wall between the suction chamber and the compression chamber, a bottom portion inside the suction chamber slopes down toward the first communicating passage such that the compression chamber side thereof is lower than the suction chamber side, and a bottom portion of the first communicating passage slopes down such that its compression chamber side is made lower, a second communicating passage being provided with the exhaust valve and communicating between the exhaust chamber and the compression chamber is formed at a bottom end of a partition wall between the exhaust chamber and the compression chamber, a bottom portion inside the compression chamber slopes down toward the second communicating passage such that the exhaust chamber side thereof is lower than the compression chamber side, and a bottom portion of the second communicating passage slopes down such that its exhaust chamber side is made lower, and a bottom portion inside the exhaust chamber slopes down toward the exhaust port such that the exhaust port side thereof is made lower, and the exhaust port slopes down such that an outlet side thereof is made lower.