A drive device includes a motor having a rotor rotatable about a motor axis, a motor housing accommodating the motor, an inverter housing accommodating an inverter electrically connected to the motor, and a gear housing accommodating a gear portion. The inverter housing opens upwardly and is arranged beside the motor housing in a direction intersecting the motor axis. The inverter housing has a bottom wall, and first through fourth side walls extending upward from the bottom wall and surrounding the bottom wall. The first and second side walls face each other, and the third and fourth side walls face each other. The inverter housing includes a first rib extending upward from the bottom wall and connecting the first side wall and the second side wall, and a second rib extending upward from the bottom wall and connecting the third side wall and the fourth side wall.