diff --git a/doc/en/source/algorithm/mapper_mpi.rst b/doc/en/source/algorithm/mapper_mpi.rst
index 36acc06d..021f0b17 100644
--- a/doc/en/source/algorithm/mapper_mpi.rst
+++ b/doc/en/source/algorithm/mapper_mpi.rst
@@ -58,9 +58,10 @@ Mesh definition file
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Define the grid space to be explored in this file.
-The first column is the index of the mesh, and the second and subsequent columns are the values of variables defined in ``string_list`` in the ``[solver.param]`` section.
+1 + ``dimension`` columns are required.
+The first column is the index of the mesh, and the second and subsequent columns are the values of parameter.
 
-Below, a sample file is shown.
+A sample file for two dimensions is shown below.
 
 .. code-block::
 
diff --git a/doc/ja/source/algorithm/mapper_mpi.rst b/doc/ja/source/algorithm/mapper_mpi.rst
index d7b327d3..716defd8 100644
--- a/doc/ja/source/algorithm/mapper_mpi.rst
+++ b/doc/ja/source/algorithm/mapper_mpi.rst
@@ -60,11 +60,12 @@ MPI 並列を行う場合は、 `mpi4py <https://mpi4py.readthedocs.io/en/stable
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 本ファイルで探索するグリッド空間を定義します。
+1 + ``dimension`` 列のテキストファイルで、
 1列目にメッシュのインデックス、
-2列目以降は ``[solver.param]`` セクションにある、
-``string_list`` で定義された変数に入る値が入ります。
+2列目以降は探索パラメータ :math:`x` に対応する値を記載します。
+また、 ``#`` から始まる行はコメントとして無視されます。
 
-以下、サンプルを記載します。
+以下、2次元パラメータ空間探索のサンプルを記載します。
 
 .. code-block::
 
diff --git a/src/py2dmat/algorithm/_algorithm.py b/src/py2dmat/algorithm/_algorithm.py
index ab2b95dd..054b1c83 100644
--- a/src/py2dmat/algorithm/_algorithm.py
+++ b/src/py2dmat/algorithm/_algorithm.py
@@ -246,6 +246,8 @@ def _meshgrid(
             data = np.loadtxt(
                 mesh_path, comments=comments, delimiter=delimiter, skiprows=skiprows,
             )
+            if data.ndim == 1:
+                data = data.reshape(1, -1)
             grid = data
         else:
             if "min_list" not in info_param:
diff --git a/src/py2dmat/algorithm/mapper_mpi.py b/src/py2dmat/algorithm/mapper_mpi.py
index 991123cb..b2f6b136 100644
--- a/src/py2dmat/algorithm/mapper_mpi.py
+++ b/src/py2dmat/algorithm/mapper_mpi.py
@@ -77,22 +77,25 @@ def _run(self) -> None:
 
                 print("mesh after:", mesh)
 
-            fx_order = np.argsort(fx_list)
-            minimum_point = []
-            print("mesh_list[fx_order[0]]:")
-            print(self.mesh_list[fx_order[0]])
-            for index in range(1, dimension + 1):
-                minimum_point.append(self.mesh_list[fx_order[0]][index])
+            if iterations > 0:
+                fx_order = np.argsort(fx_list)
+                minimum_point = []
+                print("mesh_list[fx_order[0]]:")
+                print(self.mesh_list[fx_order[0]])
+                for index in range(1, dimension + 1):
+                    minimum_point.append(self.mesh_list[fx_order[0]][index])
 
-            time_sta = time.perf_counter()
-            file_CM.write("#Minimum point :")
-            for value in minimum_point:
-                file_CM.write(" {:8f}".format(value))
-            file_CM.write("\n")
-            file_CM.write("#R-factor : {:8f}\n".format(fx_list[fx_order[0]]))
-            file_CM.write("#see Log{}\n".format(round(self.mesh_list[fx_order[0]][0])))
-            time_end = time.perf_counter()
-            self.timer["run"]["file_CM"] += time_end - time_sta
+                time_sta = time.perf_counter()
+                file_CM.write("#Minimum point :")
+                for value in minimum_point:
+                    file_CM.write(" {:8f}".format(value))
+                file_CM.write("\n")
+                file_CM.write("#R-factor : {:8f}\n".format(fx_list[fx_order[0]]))
+                file_CM.write("#see Log{}\n".format(round(self.mesh_list[fx_order[0]][0])))
+                time_end = time.perf_counter()
+                self.timer["run"]["file_CM"] += time_end - time_sta
+            else:
+                file_CM.write("# No mesh point\n")
 
         print(
             "complete main process : rank {:08d}/{:08d}".format(