\begin{tikzpicture}[
   node distance=1.5cm,
   neuron/.style={circle,draw,minimum size=0.5cm}
]
   % Input layer
   \node[neuron,fill=black] (i1) {};
   \node[neuron,fill=black] (i2) [below=0.5cm of i1] {};
   \node[neuron,fill=black] (i3) [below=0.5cm of i2] {};
   
   % Hidden layers
   \foreach \y in {1,2,3} {
       \node[neuron] (h1\y) [right=0.3cm of i\y] {};
   }
   
   % Output layer
   \node[neuron,fill=black] (o1) [right=0.2cm of h12] {};
   
   % Connections
   \foreach \i in {1,2,3}
       \foreach \j in {1,2,3}
           \draw (i\i) -- (h1\j);
           
   \foreach \i in {1,2,3}
       \draw (h1\i) -- (o1);
\end{tikzpicture} 