An optical interference measurement apparatus comprising: a light source that is configured to output measurement light; a measurement unit (10, H1, and H2) that is configured to emit the measurement light (L11 and L12) and to receive return light (L31 and L32) that is reflected from a measurement object (O1 and O2); a detector (15 and 72) that is configured to receive an interference signal of the return light (L31, L32, and L72) and reference light (L41, L42, L71, and L80) and to convert the interference signal into an electric signal and a processing unit that is configured to obtain information relating to a distance, a speed, or an oscillation of the measurement object (O1 and O2), based on the electric signal, wherein a fiber coupler that branches the measurement light from the light source is provided on an optical path between the light source and the measurement unit (10, H1, and H2), the measurement unit includes a first measurement head to which a first measurement light branched from the fiber coupler is input via a first optical path, and a second measurement head to which a second measurement light branched from the fiber coupler is input via a second optical path, a first return light that is received by the first measurement head is guided to the detector (15 and 72) via the first optical path and the fiber coupler, a second return light that is received by the second measurement head is guided to the detector (15 and 72) via the second optical path and the fiber coupler, an optical path length D1 from the fiber coupler to the leading end of the first measurement head, an optical path length D2 from the fiber coupler to the leading end of the second measurement head, a maximum optical path length R1max of the measurement range of the first measurement head, an optical path length S1 of the first reference light (L41, L71, and L80) that interferes with the first return light, and an optical path length S2 of the second reference light (L42, L71, and L80) that interferes with the second return light are set such that the relation D 1 + R 1 max - S 1 < D 2 - S 2 is satisfied, a first reference surface which is a structure for forming the first reference light by reflecting part of the first measurement light, is arranged at a connection portion of the first optical path and the first measurement head, characterised in that the first reference surface is an end face on the first measurement head side of an optical fiber that forms the first optical path. a light source that is configured to output measurement light; a measurement unit (10, H1, and H2) that is configured to emit the measurement light (L11 and L12) and to receive return light (L31 and L32) that is reflected from a measurement object (O1 and O2); a detector (15 and 72) that is configured to receive an interference signal of the return light (L31, L32, and L72) and reference light (L41, L42, L71, and L80) and to convert the interference signal into an electric signal and a processing unit that is configured to obtain information relating to a distance, a speed, or an oscillation of the measurement object (O1 and O2), based on the electric signal, wherein a fiber coupler that branches the measurement light from the light source is provided on an optical path between the light source and the measurement unit (10, H1, and H2), the measurement unit includes a first measurement head to which a first measurement light branched from the fiber coupler is input via a first optical path, and a second measurement head to which a second measurement light branched from the fiber coupler is input via a second optical path, a first return light that is received by the first measurement head is guided to the detector (15 and 72) via the first optical path and the fiber coupler, a second return light that is received by the second measurement head is guided to the detector (15 and 72) via the second optical path and the fiber coupler, an optical path length D1 from the fiber coupler to the leading end of the first measurement head, an optical path length D2 from the fiber coupler to the leading end of the second measurement head, a maximum optical path length R1max of the measurement range of the first measurement head, an optical path length S1 of the first reference light (L41, L71, and L80) that interferes with the first return light, and an optical path length S2 of the second reference light (L42, L71, and L80) that interferes with the second return light are set such that the relation D 1 + R 1 max - S 1 < D 2 - S 2 is satisfied, a first reference surface which is a structure for forming the first reference light by reflecting part of the first measurement light, is arranged at a connection portion of the first optical path and the first measurement head, characterised in that the first reference surface is an end face on the first measurement head side of an optical fiber that forms the first optical path.