Opportunity cost is one of the fundamental concepts in economics. This research note picks out two articles dealing with the current controversial topics on the concept. One is “Opportunity Cost: A reexamination” by Michael Parkin from the Journal of Economic Education (2016), the other is “Is the Concept of Opportunity Cost Crucial?” by Yasukazu Ichino from the Konan Economic Papers (2017) which is written in Japanese. The former focuses the theme on which is better to define opportunity cost as the quantity or as the value of the second-best alternative, and the latter asserts the concept of opportunity cost to be unavailable and unimportant for learning microeconomics. The author refers to and interprets the arguments of the two articles by excerpting the main sections or conclusions from them. Based on scrutiny of the articles, the objective and significance of teaching the basic economic concept at the secondary education level in Japan is considered finally.

There are two opportunity costs for vacant buildings：（i） value of the building depreciates without a usage of the building and （ii） in case service life of the building has already passed, demolition to utilize the land is delayed. A framework to estimate these costs is proposed, using a depreciation curve and data on household-owned vacant detached houses for entire Japan from Housing and Land Survey. The cost for a year is estimated as 86 billion JPY and the cumulative cost to date for current vacant houses is estimated as 651 billion JPY, mainly from the building depreciation channel at an early stage of a building life.

This paper refers to how Austrian-born concept of opportunity cost was accepted and established as a basic economic concept in current economics and economic education. The concept of opportunity cost was created by von Wieser and transferred to the United States via London. The key person who transmitted the concept to America was Robbins at LSE. There was another route of transmission of the concept; some Austrian economists like von Haberler brought it directly to the United States in the 1930’s. In the United States, this concept was accepted mainly by Chicago school economists like Knight and spread wide in the country by their hands. But the process was not straightforward, and I will trace it back to Samuelson’s Economics. The term of opportunity cost was first introduced in the 5th edition (1961) of the book. At the same time, JCEE introduced opportunity cost as a fundamental economic concept in the standard economic teaching (Task Force Report), and the concept was beginning to prevail nationwide in K-12 school education in the United States. It has become a fundamental economic concept ever since at the university level and even in the preschool education. In Japan, the concept was introduced in economics instruction at university in the 1980’s, but it was hardly taught at junior or senior high school at that time. Opportunity cost has an important role in making economic decisions. As it is an invisible cost, there is much difficulty in understanding it. Besides, opportunity cost is a subjective expense and its definition is difficult. It is necessary to teach it with firm definition and prepare many examples to make students understand the concept. A lot of effort is required to develop an economic way of thinking through opportunity cost among students.

人工林の施業計画の中で間伐作業と枝打ち作業は特に緊急性が低いと考えられ, 経済環境の悪化から遅れることが多い. 間伐作業など個々の森林作業の森林の育成への影響を評価する方法を考案した. システム収穫表の手法は林分全体の成長予測を行うのに対し, 今回は施業計画の作業実施後, 残すべき一部の立木に着目して計画との乖離を評価した. 林分密度管理図と施業体系図を活用し, 間伐効果を明示し