A speech translation device includes: a beamformer which forms, from a speech signal obtained by a microphone array, a first beam and a second beam having different directions; a direction designator which designates one of the first beam and the second beam according to a user operation; a signal-to-noise (SN) ratio calculator which calculates an SN ratio using the designated beam as a signal component in the SN ratio, and the other beam not designated as a noise component; a display determiner which determines whether recognition of the designated beam is difficult, using the calculated SN ratio, and determines a speaking instruction for overcoming difficulty of the recognition when determining that the recognition is difficult; and a display which displays the speaking instruction determined by the display determiner in a display area.