An electromagnetic radiation generating device <100> that is adapted to generate electromagnetic radiation from a plane surface, comprising: an electromagnetic radiation generating element <10, 10a, 10b> including: a depletion layer forming body <90> that forms a depletion layer by stacking a p-type semiconductor layer <14> and an n-type semiconductor layer <15> in a planar pattern; a light receiving surface electrode <12, 12a> formed on one surface of said depletion layer forming body <90>, the light receiving surface electrode <12, 12a> including a plurality of parallel electrode parts <121> that are equally spaced while a forming distance <P1> is maintained between the parallel electrode parts <121>, the forming distance <P1> corresponding to the wavelength of said electromagnetic radiation generated from said depletion layer forming body <90>; and a rear surface electrode <13> formed on the opposite surface of said depletion layer forming body <90>; a light irradiating unit <200> that is adapted to emit pulsed light <LP1> toward said electromagnetic radiation generating element <10, 10a, 10b>; and a reverse bias voltage applying circuit <11> that is adapted to apply a voltage to bring said depletion layer formed in said depletion layer forming body <90> into a reverse biased condition through said light receiving surface electrode <12, 12a> and said rear surface electrode <13>, wherein said light irradiating unit <200> includes a scanning section <30> that is adapted to scan said electromagnetic radiation generating element <10, 10a, 10b> with said pulsed light <LP1> and said scanning section <30> is adapted to apply said pulsed light <LP1> to points along each of said parallel electrode parts <121>, and to apply said pulsed light <LP1> for a required period of time at intervals in agreement with said forming distance <P1>. an electromagnetic radiation generating element <10, 10a, 10b> including: a depletion layer forming body <90> that forms a depletion layer by stacking a p-type semiconductor layer <14> and an n-type semiconductor layer <15> in a planar pattern; a light receiving surface electrode <12, 12a> formed on one surface of said depletion layer forming body <90>, the light receiving surface electrode <12, 12a> including a plurality of parallel electrode parts <121> that are equally spaced while a forming distance <P1> is maintained between the parallel electrode parts <121>, the forming distance <P1> corresponding to the wavelength of said electromagnetic radiation generated from said depletion layer forming body <90>; and a rear surface electrode <13> formed on the opposite surface of said depletion layer forming body <90>; a light irradiating unit <200> that is adapted to emit pulsed light <LP1> toward said electromagnetic radiation generating element <10, 10a, 10b>; and a reverse bias voltage applying circuit <11> that is adapted to apply a voltage to bring said depletion layer formed in said depletion layer forming body <90> into a reverse biased condition through said light receiving surface electrode <12, 12a> and said rear surface electrode <13>, wherein said light irradiating unit <200> includes a scanning section <30> that is adapted to scan said electromagnetic radiation generating element <10, 10a, 10b> with said pulsed light <LP1> and said scanning section <30> is adapted to apply said pulsed light <LP1> to points along each of said parallel electrode parts <121>, and to apply said pulsed light <LP1> for a required period of time at intervals in agreement with said forming distance <P1>.