A hologram recording/reproducing device includes a laser light source emitting laser light; a spatial light modulator generating signal light and reference light from the laser light emitted from the laser light source, the signal light and the reference light traveling in a common light path; a first relay lens system including a first shielding plate at a focal position thereof and transmitting the signal light and the reference light generated by the spatial light modulator, the first shielding plate having a pinhole whose size is 1 to 2 times a Nyquist size; a phase modulating element disposed at a conjugate plane of the signal light and the reference light transmitted through the first relay lens system; an objective lens converging the signal light and the reference light transmitted through the phase modulating element on a hologram recording medium; and a light receiving system disposed between the phase modulating element and objective lens and receiving light returning from the hologram recording medium.