diff --git a/bin/php-class-diagram b/bin/php-class-diagram
index 5ca31b3..9f539c1 100755
--- a/bin/php-class-diagram
+++ b/bin/php-class-diagram
@@ -88,7 +88,7 @@ if (empty($directory)) {
     fwrite(STDERR, $usage);
     exit(-1);
 }
-if (!is_dir($directory)) {
+if (!file_exists($directory)) {
     fwrite(STDERR, sprintf("ERROR: specified directory dose not exists. directory: %s\n", $directory));
     fwrite(STDERR, $usage);
     exit(-1);
diff --git a/src/Main.php b/src/Main.php
index 6fd8907..d36e887 100644
--- a/src/Main.php
+++ b/src/Main.php
@@ -30,6 +30,14 @@ public function run(): void
 
     private function createFinder(): Finder
     {
+        if (is_file($this->directory)) {
+            $finder = new Finder();
+            $finder->files()->in(dirname($this->directory));
+            $finder->files()->name($this->options->includes());
+
+            return $finder;
+        }
+
         $finder = new Finder();
         $finder->files()->in($this->directory);
         $finder->files()->name($this->options->includes());
@@ -62,6 +70,7 @@ private function findEntries(Finder $finder): array
                 fwrite(STDERR, $e->getMessage() . "\r\n");
             }
         }
+
         return $entries;
     }
 
@@ -74,9 +83,9 @@ private function renderEntries(array $entries): void
 
         match ($this->options->diagram()) {
             Options::DIAGRAM_CLASS => $this->renderDiagramClass($relation),
-            OPTIONS::DIAGRAM_PACKAGE => $this->renderDiagramPackage($relation),
-            OPTIONS::DIAGRAM_JIG => $this->renderDiagramJig($relation),
-            OPTIONS::DIAGRAM_DIVISION => $this->renderDiagramDivision($relation),
+            Options::DIAGRAM_PACKAGE => $this->renderDiagramPackage($relation),
+            Options::DIAGRAM_JIG => $this->renderDiagramJig($relation),
+            Options::DIAGRAM_DIVISION => $this->renderDiagramDivision($relation),
             default => throw new RuntimeException('invalid diagram.')
         };
     }