Hi Akira,
There can be several reasons why your dryer will run but not heat; fortunately iFixit has a whole troubleshooting page meant to assist you in figuring out exactly what's going on with your dryer.
[[Electric Dryer Not Heating|Electric Dryer Not Heating - iFixit Troubleshooting|new_window=true]]
Run through that troubleshooting guide then come on back and tell us what you found.
Also, it would help if you could edit your question and add the model number of your particular dryer; that way if we get into specifics of how to fix your dryer we can look up the correct procedures and parts.