An ophthalmic apparatus comprising: a light source; a measurement optical system configured to irradiate a subject eye with light from the light source and to guide reflected light from the subject eye, the measurement optical system having a measurement optical path length; a reference optical system configured to guide the light from the light source to form reference light, the reference optical system having a reference optical path length; an abnormality detection optical system configured to have an abnormality detection optical path length (L1, L2) from a zero point adjusted to a predetermined length to an end position and to guide the light from the light source to form abnormality detection light, the zero point being a point at which the reference optical path length coincides with the measurement optical path length; a light receiving element configured to receive measurement interference light and abnormality detection interference light, the measurement interference light being a combination of the reflected light from the subject eye and the reference light, the abnormality detection interference light being a combination of the abnormality detection light and the reference light, the light receiving element being configured to output measurement interference signals and abnormality detection interference signals according to the received measurement interference light and abnormality detection interference light; a processor; and a memory storing computer-readable instructions therein, wherein the end position of the optical path length (L1, L2) is set to be detected out of a measurement area of the subject eye, wherein the measurement area is an area from an anterior surface of a cornea to a retina of the subject eye, the computer-readable instructions, when executed by the processor, cause the ophthalmic apparatus to execute: obtaining the measurement interference signal and the abnormality detection measurement signal; determining that the abnormality detection interference light is abnormal when at least one of a position of a waveform in a depth direction and a shape of the waveform of an abnormality detection interference signal is out of a predetermined range, and determining that the measurement interference signal is abnormal when it is determined that the abnormality detection interference light is abnormal. a light source; a measurement optical system configured to irradiate a subject eye with light from the light source and to guide reflected light from the subject eye, the measurement optical system having a measurement optical path length; a reference optical system configured to guide the light from the light source to form reference light, the reference optical system having a reference optical path length; an abnormality detection optical system configured to have an abnormality detection optical path length (L1, L2) from a zero point adjusted to a predetermined length to an end position and to guide the light from the light source to form abnormality detection light, the zero point being a point at which the reference optical path length coincides with the measurement optical path length; a light receiving element configured to receive measurement interference light and abnormality detection interference light, the measurement interference light being a combination of the reflected light from the subject eye and the reference light, the abnormality detection interference light being a combination of the abnormality detection light and the reference light, the light receiving element being configured to output measurement interference signals and abnormality detection interference signals according to the received measurement interference light and abnormality detection interference light; a processor; and a memory storing computer-readable instructions therein, wherein the end position of the optical path length (L1, L2) is set to be detected out of a measurement area of the subject eye, wherein the measurement area is an area from an anterior surface of a cornea to a retina of the subject eye, the computer-readable instructions, when executed by the processor, cause the ophthalmic apparatus to execute: obtaining the measurement interference signal and the abnormality detection measurement signal; determining that the abnormality detection interference light is abnormal when at least one of a position of a waveform in a depth direction and a shape of the waveform of an abnormality detection interference signal is out of a predetermined range, and determining that the measurement interference signal is abnormal when it is determined that the abnormality detection interference light is abnormal.