A prepreg comprising at least constituents,, and as specified below and reinforcement fiber, wherein 90% or more of constituent exists in the depth range accounting for 20% of the prepreg thickness from the prepreg surface: epoxy resin, epoxy resin curing agent, and polymer particles insoluble in epoxy resin and falling under [Cx], and: [Cx] polymer particles giving a particle diameter distribution chart, when measured with a laser diffraction type particle size distribution analyzer and represented by the volume-based relative particle quantity as the longitudinal axis and the particle diameter as the horizontal axis, meeting the following requirements from (x-i) to (x-iii): (x-i) the chart has at least two peaks, (x-ii) the particles giving the two highest peaks have a diameter ratio in the range of 1.5 to 7, and (x-iii) the one of the two highest peaks attributable to the larger-diameter particles has a half-value width in the range of 1.1 to 3, and wherein the particles [Cx] include particles and particles: polymer particles having a sphericity in the range of 90 to 100 and a particle diameter distribution index in the range of 1.0 to 1.8 and having a glass transition temperature in the range of 80 to 180°C, measured using differential scanning calorimetry as described herein, and polymer particles having a number average particle diameter in the range of 1/10 to 2/3 of that of polymer particles. epoxy resin, epoxy resin curing agent, and polymer particles insoluble in epoxy resin and falling under [Cx], and: [Cx] polymer particles giving a particle diameter distribution chart, when measured with a laser diffraction type particle size distribution analyzer and represented by the volume-based relative particle quantity as the longitudinal axis and the particle diameter as the horizontal axis, meeting the following requirements from (x-i) to (x-iii): (x-i) the chart has at least two peaks, (x-ii) the particles giving the two highest peaks have a diameter ratio in the range of 1.5 to 7, and (x-iii) the one of the two highest peaks attributable to the larger-diameter particles has a half-value width in the range of 1.1 to 3, and wherein the particles [Cx] include particles and particles: polymer particles having a sphericity in the range of 90 to 100 and a particle diameter distribution index in the range of 1.0 to 1.8 and having a glass transition temperature in the range of 80 to 180°C, measured using differential scanning calorimetry as described herein, and polymer particles having a number average particle diameter in the range of 1/10 to 2/3 of that of polymer particles. [Cx] polymer particles giving a particle diameter distribution chart, when measured with a laser diffraction type particle size distribution analyzer and represented by the volume-based relative particle quantity as the longitudinal axis and the particle diameter as the horizontal axis, meeting the following requirements from (x-i) to (x-iii): (x-i) the chart has at least two peaks, (x-ii) the particles giving the two highest peaks have a diameter ratio in the range of 1.5 to 7, and (x-iii) the one of the two highest peaks attributable to the larger-diameter particles has a half-value width in the range of 1.1 to 3, (x-i) the chart has at least two peaks, (x-ii) the particles giving the two highest peaks have a diameter ratio in the range of 1.5 to 7, and (x-iii) the one of the two highest peaks attributable to the larger-diameter particles has a half-value width in the range of 1.1 to 3, polymer particles having a sphericity in the range of 90 to 100 and a particle diameter distribution index in the range of 1.0 to 1.8 and having a glass transition temperature in the range of 80 to 180°C, measured using differential scanning calorimetry as described herein, and polymer particles having a number average particle diameter in the range of 1/10 to 2/3 of that of polymer particles.