Disclosed are a method and a device for transmitting uplink control information (UCI) by a terminal in a wireless communication system. The UCI transmission method comprises the steps of: generating an encoding information bit stream by performing channel coding for a UCI bit stream; generating complex modulation symbols by performing modulation for the generated encoding information bit stream; spreading the complex modulation symbols in block-wise on the basis of an orthogonal sequence; and transmitting the spread complex modulation symbols to a base station. The encoding information bit stream is generated by a channel coding for circularly repeating the UCI bit stream.