A distance-measurement device comprising: a light emitting unit configured to emit distance-measurement light in a plurality of distance-measurement directions (D1 n, D1 m); a light receiving unit configured to transmit received-light information upon receiving the distance-measurement light reflected by a distance-measurement target; a calculating unit configured to transmit a light emission instruction to the light emitting unit and to receive the received-light information from the light receiving unit to calculate a measurement distance (ML1 m, ML1 n) which is a distance to the distance-measurement target based on a time difference between the light emission and the light reception; and a complementing unit configured to complement a non-measurement distance (ML2 m) of a non-distance-measurement direction (D2 m) among the plurality of distance-measurement directions (D1 m, D1 n) using measurement distances of adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2m) wherein the complementing unit is configured to complement the non-measurement distance (ML2 m) based on a complementing process that is determined according to a distance difference (ΔL) which is a difference between the measurement distances (ML1 m, ML1 n) of the adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2 m), characterised in that when the distance difference (ΔL) is in a first preset range, the complementing unit is configured to calculate the non-measurement distance (ML2 m) by a first complementing process, wherein when the distance difference (ΔL) is in a second range larger than the first range, the complementing unit is configured to calculate the non-measurement distance (ML2 m) by a second complementing process, and wherein, in the second complementing process, the weight ratio of the weight of the shorter measurement distance (ML1 S) to the weight of the longer measurement distance (ML1 L) between the measurement distances (ML1 m, ML1 n) of the adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2 m) is larger than the weight ratio of the weight of the shorter measurement distance (ML1 S) to the weight of the longer measurement distance (ML1 L) in the first complementing process. a light emitting unit configured to emit distance-measurement light in a plurality of distance-measurement directions (D1 n, D1 m); a light receiving unit configured to transmit received-light information upon receiving the distance-measurement light reflected by a distance-measurement target; a calculating unit configured to transmit a light emission instruction to the light emitting unit and to receive the received-light information from the light receiving unit to calculate a measurement distance (ML1 m, ML1 n) which is a distance to the distance-measurement target based on a time difference between the light emission and the light reception; and a complementing unit configured to complement a non-measurement distance (ML2 m) of a non-distance-measurement direction (D2 m) among the plurality of distance-measurement directions (D1 m, D1 n) using measurement distances of adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2m) wherein the complementing unit is configured to complement the non-measurement distance (ML2 m) based on a complementing process that is determined according to a distance difference (ΔL) which is a difference between the measurement distances (ML1 m, ML1 n) of the adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2 m), characterised in that when the distance difference (ΔL) is in a first preset range, the complementing unit is configured to calculate the non-measurement distance (ML2 m) by a first complementing process, wherein when the distance difference (ΔL) is in a second range larger than the first range, the complementing unit is configured to calculate the non-measurement distance (ML2 m) by a second complementing process, and wherein, in the second complementing process, the weight ratio of the weight of the shorter measurement distance (ML1 S) to the weight of the longer measurement distance (ML1 L) between the measurement distances (ML1 m, ML1 n) of the adjacent distance-measurement directions (D1 m, D1 n) on either side of the non-distance-measurement direction (D2 m) is larger than the weight ratio of the weight of the shorter measurement distance (ML1 S) to the weight of the longer measurement distance (ML1 L) in the first complementing process.