Kyoto University ACCMS NLP Group

Japanese Dependency Corpus English


We construct and publish the Japanese Dependency Corpus (JDC).

We take sentences from various domains to allow corpus users to conduct domain adaptation experiments.

The unit of JDC is word like other languages contrary to existing Japanese corpora whose unit is phrase called bunsetsu. For the definition of word, we follow "short-unit words" of the Balanced Corpus of Contemporary Written Japanese (BCCWJ), which is a mature standard created by linguists of Japanese language. The only difference is that we separate the endings of inflectional words (adjectives, verbs, and auxiliary verbs) from their stems.

The target of our research is written Japanese, which is a head-final language. We assume that in Japanese dependencies go from left to right and that every word except for the last one in a sentence depends on exactly one other word. We do not make the assumption that dependencies do not cross, because even in written Japanese such dependencies may occur in informal contexts.

Corpus Specification

Category #Sent. #Words #Char.
BCCWJ ClassA + 2012
OC 1,614 33,078 46,435
OW 1,552 62,735 90,610
OY 1,858 31,563 46,481
PB 2,254 53,037 73,194
PM 2,514 42,800 65,245
PN 2,590 57,319 83,985
subtotal 12,382 280,532 405,950
OC 500 9,846 13,752
OW 504 23,952 34,203
OY 509 9,239 13,340
PB 511 11,792 16,512
PM 495 7,415 10,396
PN 505 12,621 18,456
subtotal 3,024 74,865 106,661
subtotal 15,406 355,397 512,611
EHJ train 11,700 147,964 198,196
test 1,300 16,433 21,950
subtotal 13,000 164,397 220,146
NKN train 9,023 263,425 398,567
test 1,002 29,037 43,694
subtotal 10,025 292,462 442,262
RCP train 662 12,008 18,174
test 62 1,139 1,786
subtotal 724 13,147 19,961
JNL train 322 12,263 20,332
test 32 1,116 1,868
subtotal 354 13,379 22,200
NPT train 1,750 71,208 111,394
test 250 10,497 16,409
subtotal 2,000 81,705 127,803
total 41,509 920,487 1,345,041
The table on the right shows specifications of the JDC.

Each word, except for the root word, is annotated with its head (dependency destination). Thus the number of dependencies in a corpus is equal to the number of words minus the number of sentences.

The JDC are composed of the following sources:

For the details of each corpus, please refer to the paper.

Dependency annotation standard

We present regulations for frequent phenomena taken from our annotation guideline.

Simple sentence

Basically Japanese is an SOV language. That is to say, the word order in a simple sentence is subject, object, and verb. Almost all noun phrases have a case marker called postposition to clarify its role to the verb. The only limitation is to put the main verb phrase at the end. That is to say, subject (subj.), direct object (d-obj.), indirect object (i-obj.), and other verb modifier such as adverbial phrases are ordered freely.

Compound word

We annotate a compound word with the structure representing its meaning. Modifiers of a compound word depend on its head (in many cases with very few exceptions which modifies a part of a compound word) and there is only one dependency arc going out from the head.


Some sentences have a copular verb. Most copula sentences fall into the following type:

N 1 は/subj. N 2 だ/is

We decided that the case marker "は/subj." depends on N 2, not on the auxiliary verb "だ/is." The reason is that an auxiliary verb can be omitted especially in a that-clause or sentence coordination. The head of the case marker is always N 2 independent from the existence of an auxiliary verb.


In a coordination structure two or more phrases are concatenated by using a coordination marker. In Japanese the most frequent marker is "と/and." This marker is similar to "and" in English but we put one at each point between elements.

Dependency Parsing Experiments

Test\Train BCCWJAll full+partial
EHJ-test 96.4396.97
NKN-test 91.4392.77
RCP-test 86.6392.85
JNL-test 84.2390.59
NPT-test 87.4192.64
The parser we used is MST-based dependency parser EDA.

Training corpus:


Japanese Dependency Corpus (Ver. 2015-06) (under construction.)


EDA Dependency Parser



A Japanese Word Dependency Corpus
Shinsuke Mori, Hideki Ogura, Tetsuro Sasada
LREC, pp.753-758, 2014.
A Pointwise Approach to Training Dependency Parsers from Partially Annotated Corpora
Daniel Flannery, Yusuke Miyao, Graham Neubig, Shinsuke Mori
Natural Language Processing, Vol.19, No.3, pp.167-191, September, 2012.
Training Dependency Parsers from Partially Annotated Corpora
Daniel Flannery, Yusuke Miyao, Graham Neubig, Shinsuke Mori
IJCNLP, pp.776-784, 11/10, 2011.

Last Change: 2015/10/29 by Tetsuro Sasada
Kyoto University ACCMS NLP Group