An assembly structure for a motor drive unit for converting an input power into an alternating current (AC) power suitable for driving a motor, including: a base case ; a heat dissipation fan comprising a fan and a housing arranged outside the fan to fix the fan , the heat dissipation fan being disposed in an area of an upper portion of the base case ; a heat sink comprising a base and at least one side face portion formed by extending vertically downward from both left and right ends of the base , the heat sink being disposed on one side of the heat dissipation fan on the base case ; a middle base disposed on the heat sink , a power printed circuit board (PCB) assembly disposed on the middle base ; and a filter PCB assembly disposed over the power PCB assembly , the assembly structure comprising: at least one hook fixing portion disposed on an upper surface of the base case to correspond to a position of a front face portion of the housing ; at least one hook support disposed on the upper surface of the base case to correspond to a position of a rear face portion of the housing of said heat dissipation fan ; a first guide portion disposed on the upper surface of the base case to correspond to positions of a left side face portion and a right side face portion of the housing ; and a hook engagement portion formed on an inner surface of each of the hook fixing portion and the hook support , wherein a hole corresponding to a shape of the hook engagement portion is formed in areas corresponding to the hook engagement portion on a front surface and rear surface of the housing . a base case ; a heat dissipation fan comprising a fan and a housing arranged outside the fan to fix the fan , the heat dissipation fan being disposed in an area of an upper portion of the base case ; a heat sink comprising a base and at least one side face portion formed by extending vertically downward from both left and right ends of the base , the heat sink being disposed on one side of the heat dissipation fan on the base case ; a middle base disposed on the heat sink , a power printed circuit board (PCB) assembly disposed on the middle base ; and a filter PCB assembly disposed over the power PCB assembly , the assembly structure comprising: at least one hook fixing portion disposed on an upper surface of the base case to correspond to a position of a front face portion of the housing ; at least one hook support disposed on the upper surface of the base case to correspond to a position of a rear face portion of the housing of said heat dissipation fan ; a first guide portion disposed on the upper surface of the base case to correspond to positions of a left side face portion and a right side face portion of the housing ; and a hook engagement portion formed on an inner surface of each of the hook fixing portion and the hook support , wherein a hole corresponding to a shape of the hook engagement portion is formed in areas corresponding to the hook engagement portion on a front surface and rear surface of the housing . at least one hook fixing portion disposed on an upper surface of the base case to correspond to a position of a front face portion of the housing ; at least one hook support disposed on the upper surface of the base case to correspond to a position of a rear face portion of the housing of said heat dissipation fan ; a first guide portion disposed on the upper surface of the base case to correspond to positions of a left side face portion and a right side face portion of the housing ; and a hook engagement portion formed on an inner surface of each of the hook fixing portion and the hook support , wherein a hole corresponding to a shape of the hook engagement portion is formed in areas corresponding to the hook engagement portion on a front surface and rear surface of the housing . <EOS>