diff --git a/03.bowling/bowling.rb b/03.bowling/bowling.rb
new file mode 100755
index 0000000000..c591dbf98c
--- /dev/null
+++ b/03.bowling/bowling.rb
@@ -0,0 +1,7 @@
+#! /usr/bin/env ruby
+# frozen_string_literal: true
+
+require_relative './bowling_method'
+
+frames = format_score(ARGV[0])
+puts sum_score(frames)
diff --git a/03.bowling/bowling_method.rb b/03.bowling/bowling_method.rb
new file mode 100644
index 0000000000..f4dba1fa39
--- /dev/null
+++ b/03.bowling/bowling_method.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+def to_int_scores(strings_scores)
+  converted_array = []
+  strings_scores.each do |score|
+    if score == 'X'
+      converted_array << 10
+      converted_array << 0
+    else
+      converted_array.push(score.to_i)
+    end
+  end
+  converted_array
+end
+
+def parse_scores(raw_scores)
+  scores = raw_scores.split(',')
+  int_scores = to_int_scores(scores)
+  # 10フレーム目でストライクかスペアを出すとframesの要素数が10以上になる。こうすることで10フレーム目のストライク、スペアの得点加算も通常と同じ処理で済むのでこの形にしてある
+  int_scores.each_slice(2).to_a
+end
+
+def strike?(frame)
+  frame[0] == 10
+end
+
+def spare?(frame)
+  frame[0] + frame[1] == 10
+end
+
+def calc_strike_bonus(index, frames)
+  next_index = index + 1
+  next_frame = frames[next_index]
+  if strike? next_frame
+    after_next_frame = frames[next_index + 1]
+    next_frame[0] + after_next_frame[0]
+  else
+    next_frame[0] + next_frame[1]
+  end
+end
+
+def calc_spare_bonus(index, frames)
+  next_index = index + 1
+  next_frame = frames[next_index]
+  next_frame[0]
+end
+
+def sum_score(frames)
+  total_score = 0
+  total_frames = 10
+  total_frames.times do |index|
+    frame = frames[index]
+    total_score += frame[0] + frame[1]
+    if strike?(frame)
+      total_score += calc_strike_bonus(index, frames)
+    elsif spare?(frame)
+      total_score += calc_spare_bonus(index, frames)
+    end
+  end
+  total_score
+end