The present invention relates to a block toy formed as one frame and having a magnet embedded therein, and a surface structure for joining blocks of the block toy, wherein the blocks of the block toy are formed as one frame and have magnet-embedded members coupled to the frame, and protrusion-shaped and groove-shaped structures are formed on the surface of the magnet-embedded member such that the protrusion-shaped and groove-shaped structures, formed on the surface of each magnet-embedded member, are naturally engaged with each other so as to enable the respective blocks to be securely joined to each other when the blocks are vertically joined, perpendicularly joined, and horizontally joined.
