diff --git a/PrinciplesSystemDesign/README.md b/PrinciplesSystemDesign/README.md
new file mode 100644
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--- /dev/null
+++ b/PrinciplesSystemDesign/README.md
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+### 現場で役立つシステム設計の原則
+
+本を読むとちょくちょくサンプルコードがJavaで紹介されて出てきます。  
+これをPHPで写経して体現的に内容を学ぶ事を目的にしています。
+
+### 参考資料
+
+- [現場で役立つシステム設計の原則 - Fendo181](https://scrapbox.io/fendo181/%E7%8F%BE%E5%A0%B4%E3%81%A7%E5%BD%B9%E7%AB%8B%E3%81%A4%E3%82%B7%E3%82%B9%E3%83%86%E3%83%A0%E8%A8%AD%E8%A8%88%E3%81%AE%E5%8E%9F%E5%89%87)
+
diff --git a/PrinciplesSystemDesign/chap1/Quantity.php b/PrinciplesSystemDesign/chap1/Quantity.php
new file mode 100644
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+++ b/PrinciplesSystemDesign/chap1/Quantity.php
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+<?php
+
+class Quantity
+{
+    private const MIN =1;
+    private const MAX =100;
+    public $value;
+
+    public function __construct(int $value)
+    {
+        try{
+            if($value < self::MIN) {
+                throw new Exception('1未満です');
+            }elseif ($value > self::MAX) {
+                throw new Exception('100以上です');
+            }
+        }catch (Exception $e ) {
+            echo '捕捉した例外: ',  $e->getMessage(), "\n";
+        }
+
+        $this->value = $value;
+    }
+
+    private function addValue($other) {
+        $sum = $this->value + $other;
+        return $sum;
+    }
+
+
+    public function canAdd(int $other) :bool {
+        $added = self::addValue($other);
+        return $added <= self::MAX;
+    }
+
+    public function add(int $other) {
+
+        try{
+            if(!$this->canAdd($other)) {
+                throw new Exception('合計が100を超えています');
+            }
+            $added = $this->addValue($other);
+            // addすると新しいオブジェクトを呼び出す
+            return new Quantity($added);
+
+        }catch (Exception $e){
+            echo '捕捉した例外: ',  $e->getMessage(), "\n";
+        }
+    }
+}
+
+// これで一回新しいオブジェクトを生成する
+$quanty = new Quantity(10);
+echo $quanty->value;
+
+// 新しいオブジェクトを生成する
+$quanty->add(100);
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diff --git a/PrinciplesSystemDesign/chap1/ShippingCost.php b/PrinciplesSystemDesign/chap1/ShippingCost.php
new file mode 100644
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+++ b/PrinciplesSystemDesign/chap1/ShippingCost.php
@@ -0,0 +1,30 @@
+<?php
+
+class ShippingCost
+{
+    static $minimumForFreeCost = 5000;
+    static $cost = 500;
+
+    private $basePrice;
+
+    public function __construct(int $basePrice){
+        $this->basePrice = $basePrice;
+    }
+
+    public function amount () :int{
+        if( $this->basePrice < self::$minimumForFreeCost) return self::$cost;
+        return 0;
+    }
+}
+
+function shippingCost(int $basePrice) :int {
+    $cost = new ShippingCost($basePrice);
+    return  $cost->amount();
+}
+
+echo '送料の料金は'.shippingCost(1000);
+echo '送料の料金は'.shippingCost(5000);
+
+
+
+
diff --git a/PrinciplesSystemDesign/chap2/guard.php b/PrinciplesSystemDesign/chap2/guard.php
new file mode 100644
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+++ b/PrinciplesSystemDesign/chap2/guard.php
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+<?php
+
+function free($age) {
+    if($age >= 18) return 'OK!';
+    if($age > 15) return 'So So';
+    if($age < 18) return 'NO!;';
+}
+
+$result = free(18);
+echo $result;
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diff --git a/PrinciplesSystemDesign/chap3/Person.php b/PrinciplesSystemDesign/chap3/Person.php
new file mode 100644
index 0000000..0864be9
--- /dev/null
+++ b/PrinciplesSystemDesign/chap3/Person.php
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+<?php
+
+class Person
+{
+    private $firstName;
+    protected $lastName;
+
+    public function __construct($firstName,$lastName)
+    {
+        $this->firstName = $firstName;
+        $this->lastName = $lastName;
+    }
+
+    public function fullName() {
+        return "MyName is {$this->firstName}.{$this->lastName}";
+    }
+
+}
+
+$endo = new Person("Endo","Futoshi");
+echo  $endo->fullName();
+