diff --git a/app/Plan/JsonPlanRepository.php b/app/Plan/JsonPlanRepository.php
index 8a88838..8c73d8a 100644
--- a/app/Plan/JsonPlanRepository.php
+++ b/app/Plan/JsonPlanRepository.php
@@ -90,4 +90,29 @@ class JsonPlanRepository implements PlanRepository
 
         return $maxId + 1;
     }
+
+    public function findByUser(User $user): array
+    {
+        $plans = array_filter(
+            $this->readPlans(),
+            function ($data) use ($user) {
+                return $data['userId'] === $user->getId();
+            }
+        );
+
+        return array_map(
+            function ($data) {
+                $user = $this->userRepository->find($data['userId']);
+                if ($user === null) {
+                    return null;
+                }
+                return new Plan(
+                    id: $data['id'],
+                    name: $data['name'],
+                    user: $user,
+                );
+            },
+            $plans
+        );
+    }
 }
diff --git a/app/Plan/PlanRepository.php b/app/Plan/PlanRepository.php
index a962c0f..0585edc 100644
--- a/app/Plan/PlanRepository.php
+++ b/app/Plan/PlanRepository.php
@@ -2,8 +2,14 @@
 
 namespace App\Plan;
 
+use App\User\User;
+
 interface PlanRepository
 {
     public function create(CreatePlanDto $dto): Plan;
     public function find(int $id): ?Plan;
+    /**
+     * @return Plan[]
+     */
+    public function findByUser(User $user): array;
 }
diff --git a/tests/Fakes/FakePlanRepository.php b/tests/Fakes/FakePlanRepository.php
index 45e2e85..8c18b00 100644
--- a/tests/Fakes/FakePlanRepository.php
+++ b/tests/Fakes/FakePlanRepository.php
@@ -5,9 +5,13 @@ namespace Tests\Fakes;
 use App\Plan\CreatePlanDto;
 use App\Plan\Plan;
 use App\Plan\PlanRepository;
+use App\User\User;
 
 class FakePlanRepository implements PlanRepository
 {
+    /**
+     * @var Plan[]
+     */
     private array $existingPlans = [];
 
     public function create(CreatePlanDto $dto): Plan
@@ -37,4 +41,24 @@ class FakePlanRepository implements PlanRepository
             }
         );
     }
+
+    public function findByUser(User $user): array
+    {
+        $plans = array_filter(
+            $this->existingPlans,
+            function (Plan $plan) use ($user) {
+                return $plan->getUser()->getId() === $user->getId();
+            }
+        );
+        return array_map(
+            function (Plan $plan) {
+                return new Plan(
+                    id: $plan->getId(),
+                    name: $plan->getName(),
+                    user: $plan->getUser(),
+                );
+            },
+            $plans
+        );
+    }
 }