A magnetic cooling apparatus comprising: at least one magnetic regenerator allowing a heat transfer fluid having specific heat c p_fluid J/Kg • K and density ρ g/cm 3 to pass therethrough and provided with a magnetocaloric material having specific heat c p_MCM J/Kg • K and mass m MCM g; a magnet configured to apply a magnetic field to the magnetic regenerator at a driving frequency of f Hz Hz; at least one high temperature heat exchanger allowing heat to be dissipated by the heat transfer fluid containing heat received from the magnetic regenerator subject to the magnetic field of the magnet applied thereto; at least one low temperature heat exchanger allowing heat to be absorbed by the heat transfer fluid that has transferred heat to the magnetic regenerator from which the magnetic field of the magnet has been removed; a pipe having diameter D cm and cross sectional area A cm 2 to connect the magnetic regenerator, the high temperature heat exchanger, and the low temperature heat exchanger such that the heat transfer fluid circulates through the magnetic regenerator, the high temperature heat exchanger, and the low temperature heat exchanger; and a fluid transport unit configured to circulate or reciprocate the heat transfer fluid through the pipe at a mass flow rate of m' flow g/sec, characterised in that the low temperature heat exchanger is disposed such that a distance of flow of the heat transfer fluid between an outlet of the magnetic regenerator from which the magnetic field of the magnet has been removed and an outlet of the low temperature heat exchanger is equal to, or shorter than, an effective heat exchange distance determined in the following equation in order that the heat transfer fluid effectively absorbs heat upon arriving at the low temperature heat exchanger after transferring heat to the magnetic regenerator from which the magnetic field of the magnet has been removed: S = U × m MCM × c p _ MCM / ρ × A × c p _ fluid, and U = m ′ flow × c p _ fluid × t flow / m MCM × c p _ MCM, where 0 < U < 2, A = D 2 π / 4, and t flow = 1/2f Hz, where t flow is time taken to supply fluid (sec). at least one magnetic regenerator allowing a heat transfer fluid having specific heat c p_fluid J/Kg • K and density ρ g/cm 3 to pass therethrough and provided with a magnetocaloric material having specific heat c p_MCM J/Kg • K and mass m MCM g; a magnet configured to apply a magnetic field to the magnetic regenerator at a driving frequency of f Hz Hz; at least one high temperature heat exchanger allowing heat to be dissipated by the heat transfer fluid containing heat received from the magnetic regenerator subject to the magnetic field of the magnet applied thereto; at least one low temperature heat exchanger allowing heat to be absorbed by the heat transfer fluid that has transferred heat to the magnetic regenerator from which the magnetic field of the magnet has been removed; a pipe having diameter D cm and cross sectional area A cm 2 to connect the magnetic regenerator, the high temperature heat exchanger, and the low temperature heat exchanger such that the heat transfer fluid circulates through the magnetic regenerator, the high temperature heat exchanger, and the low temperature heat exchanger; and a fluid transport unit configured to circulate or reciprocate the heat transfer fluid through the pipe at a mass flow rate of m' flow g/sec, characterised in that the low temperature heat exchanger is disposed such that a distance of flow of the heat transfer fluid between an outlet of the magnetic regenerator from which the magnetic field of the magnet has been removed and an outlet of the low temperature heat exchanger is equal to, or shorter than, an effective heat exchange distance determined in the following equation in order that the heat transfer fluid effectively absorbs heat upon arriving at the low temperature heat exchanger after transferring heat to the magnetic regenerator from which the magnetic field of the magnet has been removed: S = U × m MCM × c p _ MCM / ρ × A × c p _ fluid, and U = m ′ flow × c p _ fluid × t flow / m MCM × c p _ MCM, where 0 < U < 2, A = D 2 π / 4, and t flow = 1/2f Hz, where t flow is time taken to supply fluid (sec).