\documentclass{article}

\usepackage{pgf,tikz}
\RequirePackage[utf8]{inputenc}
\usetikzlibrary{positioning,shapes,arrows,decorations.pathreplacing,backgrounds,snakes}


\begin{document}

\begin{figure}
  \begin{center}
    \begin{tikzpicture}[scale=0.75]
      \draw (-12, 0) node[ellipse, draw, minimum width=2.0cm, minimum height=1.5cm] {Zustand 1};
      \draw ( -6, 0) node[ellipse, draw, minimum width=2.0cm, minimum height=1.5cm] {Zustand 2};
      \draw   (0, 0) node[ellipse, draw, minimum width=2.0cm, minimum height=1.5cm] {Zustand 3};
      \draw (6.5, 0) node[ellipse, draw, minimum width=2.0cm, minimum height=1.5cm] {Zustand 4};
      \draw  (-3,-6) node[ellipse, draw, minimum width=2.0cm, minimum height=1.5cm] {Zustand 5};
      
      \draw[->,line width=0.5mm] (-10.5,   0) -- node[midway,above] {Übergang 1}          	(-7.5,   0);
      \draw[->,line width=0.5mm] ( -4.5, 0.5) -- node[midway,above] {Übergang 2}          	(-1.5, 0.5); 
      \draw[->,line width=0.5mm, align=center] ( -1.5,-0.5) -- node[midway,below] {Übergang 3}	(-4.5,-0.5);
      \draw[->,line width=0.5mm] (    0,  -1) -- node[midway,right] {Übergang 4} 	(-1.7,-5.5); 
      \draw[->,line width=0.5mm] ( -4.3,-5.5) -- node[midway,left ] {Übergang 5} 	(  -6,  -1); 
      \draw[->,line width=0.5mm] (  1.5,   0) -- node[midway,above] {Übergang 6}           	( 4.5,   0); 
    \end{tikzpicture}
  \end{center}
  \caption{Prozessmodell mit fünf Zuständen}
  \label{fig:loesung}
\end{figure}

\end{document}