A steering device of a small watercraft is disclosed. The device includes a steering column oriented substantially in the vertical direction, wherein the steering column includes an upper component and a lower component, the components being coupled together so as to be movable relative to each other in the longitudinal direction thereof, and a fastening device configured to lock the relative movement of the components. One of the components includes an elongated hole which penetrates in the left-and-right direction and is elongated in the vertical direction. The other component includes a protrusion extended in the left-and-right direction so as to be accommodated in the elongated hole and to be guided by the hole in the vertical direction. The components each include a contact surface having a plurality of teeth arranged in the vertical direction, and engage with each other in the front-and-rear direction by engaging the teeth.