An intake device of an outboard motor including: an engine; an engine cover covering the engine; and an engine room formed inside the engine cover, the intake device of the outboard motor comprising: an upper cover attached to an upper surface of the engine cover; an outside air intake port formed in the upper cover; a throttle body through which outside air taken in through the outside air intake port is supplied to the engine; and an intake chamber formed between the upper cover and the engine cover and communicating with the outside air intake port and an upstream end of the throttle body, wherein the intake chamber is isolated from the engine room, a plate isolating the intake chamber from the engine room, wherein the intake chamber is isolated from the engine room by the plate, a drain path (111, 112) that communicates with an internal space and external space of the intake chamber and through which water that has intruded into the internal space of the intake chamber is allowed to be drained to the external space of the intake chamber, characterized in that the plate is provided with a bottom wall including an upper area and a lower area, and a throttle body coupling pipe through which outside air taken into the intake chamber is supplied to the throttle body communicates with the upper area of the bottom wall, and the drain path (111, 112) communicates with the lower area of the bottom wall. an engine; an engine cover covering the engine; and an engine room formed inside the engine cover, the intake device of the outboard motor comprising: an upper cover attached to an upper surface of the engine cover; an outside air intake port formed in the upper cover; a throttle body through which outside air taken in through the outside air intake port is supplied to the engine; and an intake chamber formed between the upper cover and the engine cover and communicating with the outside air intake port and an upstream end of the throttle body, wherein the intake chamber is isolated from the engine room, a plate isolating the intake chamber from the engine room, wherein the intake chamber is isolated from the engine room by the plate, a drain path (111, 112) that communicates with an internal space and external space of the intake chamber and through which water that has intruded into the internal space of the intake chamber is allowed to be drained to the external space of the intake chamber, characterized in that the plate is provided with a bottom wall including an upper area and a lower area, and a throttle body coupling pipe through which outside air taken into the intake chamber is supplied to the throttle body communicates with the upper area of the bottom wall, and the drain path (111, 112) communicates with the lower area of the bottom wall. an upper cover attached to an upper surface of the engine cover; an outside air intake port formed in the upper cover; a throttle body through which outside air taken in through the outside air intake port is supplied to the engine; and an intake chamber formed between the upper cover and the engine cover and communicating with the outside air intake port and an upstream end of the throttle body, wherein the intake chamber is isolated from the engine room, a plate isolating the intake chamber from the engine room, wherein the intake chamber is isolated from the engine room by the plate, a drain path (111, 112) that communicates with an internal space and external space of the intake chamber and through which water that has intruded into the internal space of the intake chamber is allowed to be drained to the external space of the intake chamber, characterized in that the plate is provided with a bottom wall including an upper area and a lower area, and a throttle body coupling pipe through which outside air taken into the intake chamber is supplied to the throttle body communicates with the upper area of the bottom wall, and the drain path (111, 112) communicates with the lower area of the bottom wall.