An electromagnetic wave detection apparatus comprising: an image forming unit configured to form an image of incident electromagnetic waves; a prism having a first emission surface for emitting electromagnetic waves incident from the image forming unit; a progression unit that includes a plurality of pixels (px) arranged along a reference surface (ss) and is configured to cause electromagnetic waves incident on the reference surface (ss) from the first emission surface to progress in a particular direction using each of the pixels (px); and a first detector configured to detect electromagnetic waves, wherein the prism includes a reflection suppressor (900a, 900b) that is provided at a position out of a progression path of electromagnetic waves incident from the image forming unit to be detected by the first detector and suppresses unnecessary light caused by end surface reflection of the prism from being incident on the first detector, wherein the reflection suppressor (900a, 900b) is provided on the surface of the prism, the electromagnetic wave detection apparatus further comprises a second detector configured to detect electromagnetic waves, the prism includes a first prism having a second surface configured to reflect a part of the electromagnetic waves and transmit the other part, and a third surface configured to transmit the electromagnetic waves reflected by the second surface and cause to progress to the second detector, characterized in a second prism having a fourth surface configured to cause the electromagnetic waves transmitted through the second surface to progress to the progression unit, a fifth surface configured to progress the electromagnetic waves transmitted through the second surface to the fourth surface, and a sixth surface configured to transmit the electromagnetic waves reflected by the fifth surface and cause to progress to the first detector, and a third prism having a surface that opposes to the second surface, a surface that opposes to the fifth surface, and an eighth surface that intersects with these surfaces, and is arranged between the first prism and the second prism, and the fifth surface reflects the electromagnetic waves progressed in the particular direction and causes to progress to the sixth surface. an image forming unit configured to form an image of incident electromagnetic waves; a prism having a first emission surface for emitting electromagnetic waves incident from the image forming unit; a progression unit that includes a plurality of pixels (px) arranged along a reference surface (ss) and is configured to cause electromagnetic waves incident on the reference surface (ss) from the first emission surface to progress in a particular direction using each of the pixels (px); and a first detector configured to detect electromagnetic waves, wherein the prism includes a reflection suppressor (900a, 900b) that is provided at a position out of a progression path of electromagnetic waves incident from the image forming unit to be detected by the first detector and suppresses unnecessary light caused by end surface reflection of the prism from being incident on the first detector, wherein the reflection suppressor (900a, 900b) is provided on the surface of the prism, the electromagnetic wave detection apparatus further comprises a second detector configured to detect electromagnetic waves, the prism includes a first prism having a second surface configured to reflect a part of the electromagnetic waves and transmit the other part, and a third surface configured to transmit the electromagnetic waves reflected by the second surface and cause to progress to the second detector, characterized in a second prism having a fourth surface configured to cause the electromagnetic waves transmitted through the second surface to progress to the progression unit, a fifth surface configured to progress the electromagnetic waves transmitted through the second surface to the fourth surface, and a sixth surface configured to transmit the electromagnetic waves reflected by the fifth surface and cause to progress to the first detector, and a third prism having a surface that opposes to the second surface, a surface that opposes to the fifth surface, and an eighth surface that intersects with these surfaces, and is arranged between the first prism and the second prism, and a first prism having a second surface configured to reflect a part of the electromagnetic waves and transmit the other part, and a third surface configured to transmit the electromagnetic waves reflected by the second surface and cause to progress to the second detector, characterized in a second prism having a fourth surface configured to cause the electromagnetic waves transmitted through the second surface to progress to the progression unit, a fifth surface configured to progress the electromagnetic waves transmitted through the second surface to the fourth surface, and a sixth surface configured to transmit the electromagnetic waves reflected by the fifth surface and cause to progress to the first detector, and a third prism having a surface that opposes to the second surface, a surface that opposes to the fifth surface, and an eighth surface that intersects with these surfaces, and is arranged between the first prism and the second prism, and the fifth surface reflects the electromagnetic waves progressed in the particular direction and causes to progress to the sixth surface.